The world's population first reached one billion people in 1803, and reach eight billion in 2023, and will peak at almost 11 billion by the end of the century. Although it took thousands of years to reach one billion people, it did so at the beginning of a phenomenon known as the demographic transition; from this point onwards, population growth has skyrocketed, and since the 1960s the population has increased by one billion people every 12 to 15 years. The demographic transition sees a sharp drop in mortality due to factors such as vaccination, sanitation, and improved food supply; the population boom that follows is due to increased survival rates among children and higher life expectancy among the general population; and fertility then drops in response to this population growth. Regional differences The demographic transition is a global phenomenon, but it has taken place at different times across the world. The industrialized countries of Europe and North America were the first to go through this process, followed by some states in the Western Pacific. Latin America's population then began growing at the turn of the 20th century, but the most significant period of global population growth occurred as Asia progressed in the late-1900s. As of the early 21st century, almost two thirds of the world's population live in Asia, although this is set to change significantly in the coming decades. Future growth The growth of Africa's population, particularly in Sub-Saharan Africa, will have the largest impact on global demographics in this century. From 2000 to 2100, it is expected that Africa's population will have increased by a factor of almost five. It overtook Europe in size in the late 1990s, and overtook the Americas a decade later. In contrast to Africa, Europe's population is now in decline, as birth rates are consistently below death rates in many countries, especially in the south and east, resulting in natural population decline. Similarly, the population of the Americas and Asia are expected to go into decline in the second half of this century, and only Oceania's population will still be growing alongside Africa. By 2100, the world's population will have over three billion more than today, with the vast majority of this concentrated in Africa. Demographers predict that climate change is exacerbating many of the challenges that currently hinder progress in Africa, such as political and food instability; if Africa's transition is prolonged, then it may result in further population growth that would place a strain on the region's resources, however, curbing this growth earlier would alleviate some of the pressure created by climate change.

In 1800, the present-day region of Mexico had a population of just over six million people. Mexico gained its independence from the Spanish crown in 1821, and population growth remained steady for the next 85 years. Growth then halted with with the Panic of 1907, an American financial crisis whose ripple effects in Mexico would set the stage for the Mexican Revolution in 1910. This revolution would see population flatline at just over fifteen million between 1910 and 1920, as widespread conflict and result in the death of between 1.7 to 2.7 million over the decade, and the coinciding 1918 Spanish Flu epidemic would see the loss of another 300,000 in this time period. Following the end of both the Mexican Revolution and the Spanish Flu epidemic in 1920, the population of Mexico would begin to increase rapidly as modernization would see mortality rates fall and standards of living rise throughout the country. This growth has continued steadily into the 21st century, and in 2020, Mexico is estimated to have a population of just under 129 million.

The history of modern Brazil begins in the year 1500 when Pedro Álvares Cabral arrived with a small fleet and claimed the land for the Portuguese Empire. With the Treaty of Torsedillas in 1494, Spain and Portugal agreed to split the New World peacefully, thus allowing Portugal to take control of the area with little competition from other European powers. As the Portuguese did not arrive with large numbers, and the indigenous population was overwhelmed with disease, large numbers of African slaves were transported across the Atlantic and forced to harvest or mine Brazil's wealth of natural resources. These slaves were forced to work in sugar, coffee and rubber plantations and gold and diamond mines, which helped fund Portuguese expansion across the globe. In modern history, transatlantic slavery brought more Africans to Brazil than any other country in the world. This combination of European, African and indigenous peoples set the foundation for what has become one of the most ethnically diverse countries across the globe.

Independence and Monarchy By the early eighteenth century, Portugal had established control over most of modern-day Brazil, and the population more than doubled in each half of the 1800s. The capital of the Portuguese empire was moved to Rio de Janeiro in 1808 (as Napoleon's forces moved closer towards Lisbon), making this the only time in European history where a capital was moved to another continent. The United Kingdom of Portugal, Brazil and the Algarves was established in 1815, and when the Portuguese monarchy and capital returned to Lisbon in 1821, the King's son, Dom Pedro, remained in Brazil as regent. The following year, Dom Pedro declared Brazil's independence, and within three years, most other major powers (including Portugal) recognized the Empire of Brazil as an independent monarchy and formed economic relations with it; this was a much more peaceful transition to independence than many of the ex-Spanish colonies in the Americas. Under the reign of Dom Pedro II, Brazil's political stability remained relatively intact, and the economy grew through its exportation of raw materials and economic alliances with Portugal and Britain. Despite pressure from political opponents, Pedro II abolished slavery in 1850 (as part of a trade agreement with Britain), and Brazil remained a powerful, stable and progressive nation under Pedro II's leadership, in stark contrast to its South American neighbors. The booming economy also attracted millions of migrants from Europe and Asia around the turn of the twentieth century, which has had a profound impact on Brazil's demography and culture to this day.

The New Republic

Despite his popularity, King Pedro II was overthrown in a military coup in 1889, ending his 58 year reign and initiating six decades of political instability and economic difficulties. A series of military coups, failed attempts to restore stability, and the decline of Brazil's overseas influence contributed greatly to a weakened economy in the early 1900s. The 1930s saw the emergence of Getúlio Vargas, who ruled as a fascist dictator for two decades. Despite a growing economy and Brazil's alliance with the Allied Powers in the Second World War, the end of fascism in Europe weakened Vargas' position in Brazil, and he was eventually overthrown by the military, who then re-introduced democracy to Brazil in 1945. Vargas was then elected to power in 1951, and remained popular among the general public, however political opposition to his beliefs and methods led to his suicide in 1954. Further political instability ensued and a brutal, yet prosperous, military dictatorship took control in the 1960s and 1970s, but Brazil gradually returned to a democratic nation in the 1980s. Brazil's economic and political stability fluctuated over the subsequent four decades, and a corruption scandal in the 2010s saw the impeachment of President Dilma Rousseff. Despite all of this economic instability and political turmoil, Brazil is one of the world's largest economies and is sometimes seen as a potential superpower. The World Bank classifies it as a upper-middle income country and it has the largest share of global wealth in Latin America. It is the largest Lusophone (Portuguese-speaking), and sixth most populous country in the world, with a population of more than 210 million people.

In the past four centuries, the population of the United States has grown from a recorded 350 people around the Jamestown colony of Virginia in 1610, to an estimated 331 million people in 2020. The pre-colonization populations of the indigenous peoples of the Americas have proven difficult for historians to estimate, as their numbers decreased rapidly following the introduction of European diseases (namely smallpox, plague and influenza). Native Americans were also omitted from most censuses conducted before the twentieth century, therefore the actual population of what we now know as the United States would have been much higher than the official census data from before 1800, but it is unclear by how much. Population growth in the colonies throughout the eighteenth century has primarily been attributed to migration from the British Isles and the Transatlantic slave trade; however it is also difficult to assert the ethnic-makeup of the population in these years as accurate migration records were not kept until after the 1820s, at which point the importation of slaves had also been illegalized. Nineteenth century In the year 1800, it is estimated that the population across the present-day United States was around six million people, with the population in the 16 admitted states numbering at 5.3 million. Migration to the United States began to happen on a large scale in the mid-nineteenth century, with the first major waves coming from Ireland, Britain and Germany. In some aspects, this wave of mass migration balanced out the demographic impacts of the American Civil War, which was the deadliest war in U.S. history with approximately 620 thousand fatalities between 1861 and 1865. The civil war also resulted in the emancipation of around four million slaves across the south; many of whose ancestors would take part in the Great Northern Migration in the early 1900s, which saw around six million black Americans migrate away from the south in one of the largest demographic shifts in U.S. history. By the end of the nineteenth century, improvements in transport technology and increasing economic opportunities saw migration to the United States increase further, particularly from southern and Eastern Europe, and in the first decade of the 1900s the number of migrants to the U.S. exceeded one million people in some years. Twentieth and twenty-first century The U.S. population has grown steadily throughout the past 120 years, reaching one hundred million in the 1910s, two hundred million in the 1960s, and three hundred million in 2007. In the past century, the U.S. established itself as a global superpower, with the world's largest economy (by nominal GDP) and most powerful military. Involvement in foreign wars has resulted in over 620,000 further U.S. fatalities since the Civil War, and migration fell drastically during the World Wars and Great Depression; however the population continuously grew in these years as the total fertility rate remained above two births per woman, and life expectancy increased (except during the Spanish Flu pandemic of 1918).

Since the Second World War, Latin America has replaced Europe as the most common point of origin for migrants, with Hispanic populations growing rapidly across the south and border states. Because of this, the proportion of non-Hispanic whites, which has been the most dominant ethnicity in the U.S. since records began, has dropped more rapidly in recent decades. Ethnic minorities also have a much higher birth rate than non-Hispanic whites, further contributing to this decline, and the share of non-Hispanic whites is expected to fall below fifty percent of the U.S. population by the mid-2000s. In 2020, the United States has the third-largest population in the world (after China and India), and the population is expected to reach four hundred million in the 2050s.

In 1800, the population of Yemen was just under 2.6 million, and would gradually grow to just 3.2 million by the end of the 18th century. Between the mid-1800s and early-1900s, the north and south regions of present-day Yemen had been split into territories of the British and Ottoman empires respectively; the north became independent in 1918, during Ottoman dissolution, while the British did not withdraw from the region until 1967. Yemen would experience an exponential growth in population in the years beginning in the 1970s, following the discovery of petroleum in the country, though this would slow somewhat in the 1990s, in part the result of food shortages and instability throughout the country years following the unification of South Yemen and the Yemen Arab Republic. In 2020, the population of Yemen is estimated to be just under thirty million people, however, the country has been experiencing a civil war in since 2015, which has resulted in one of the most severe humanitarian crises in recent history, with over 100,000 deaths (mostly children, due to famine) as well as the displacement of millions of people, and one of the most severe cholera outbreaks in recent decades.

In 1800, the region of present-day Switzerland had a population of approximately 1.8 million people. This figure would grow steadily throughout the 19th century, as political and religious grievances gave way to a united federation, whose economic policies saw Switzerland emerge as one of Europe's most prosperous and stable countries. Growth boomed between 1890 and 1910, as industrialization would see significant economic growth and migration to the country. While Switzerland’s neutrality in both World Wars would prevent the mass fatalities experienced across the rest of Europe during the early 20th century, Switzerland’s population would nevertheless stagnate in both the First and Second World War and in the Great Depression in the 1930s, as the economic turmoil and conflict abroad would halt the migration that had previously driven population growth.

Following the end of the Second World War, growth would resume and would rise steadily until the late 1970s, before an economic recession saw the population fall again as workers migrated in search of employment elsewhere. However, population growth has steadily risen since the 1980s, reaching seven million in the mid-1990s and eight million in 2012. Today, with a population of 8.7 million, Switzerland is ranked among the wealthiest and most developed nations in the world, with very high standards of living.

In 1800, the population of Japan was just over 30 million, a figure which would grow by just two million in the first half of the 19th century. However, with the fall of the Tokugawa shogunate and the restoration of the emperor in the Meiji Restoration of 1868, Japan would begin transforming from an isolated feudal island, to a modernized empire built on Western models. The Meiji period would see a rapid rise in the population of Japan, as industrialization and advancements in healthcare lead to a significant reduction in child mortality rates, while the creation overseas colonies would lead to a strong economic boom. However, this growth would slow beginning in 1937, as Japan entered a prolonged war with the Republic of China, which later grew into a major theater of the Second World War. The war was eventually brought to Japan's home front, with the escalation of Allied air raids on Japanese urban centers from 1944 onwards (Tokyo was the most-bombed city of the Second World War). By the war's end in 1945 and the subsequent occupation of the island by the Allied military, Japan had suffered over two and a half million military fatalities, and over one million civilian deaths.

The population figures of Japan were quick to recover, as the post-war “economic miracle” would see an unprecedented expansion of the Japanese economy, and would lead to the country becoming one of the first fully industrialized nations in East Asia. As living standards rose, the population of Japan would increase from 77 million in 1945, to over 127 million by the end of the century. However, growth would begin to slow in the late 1980s, as birth rates and migration rates fell, and Japan eventually grew to have one of the oldest populations in the world. The population would peak in 2008 at just over 128 million, but has consistently fallen each year since then, as the fertility rate of the country remains below replacement level (despite government initiatives to counter this) and the country's immigrant population remains relatively stable. The population of Japan is expected to continue its decline in the coming years, and in 2020, it is estimated that approximately 126 million people inhabit the island country.

In 1800, the population of the area of modern-day Slovakia was estimated to be just over two million, a figure which would grow steadily throughout the 19th century as part of the kingdom of Hungary and later under the dual kingdom of Austria-Hungary. This growth would continue even throughout the first half of the 20th century, as the country would largely escape conflict in both the First and Second World Wars. As a result, Slovakia’s population would rise to just under three and a half million by 1950.

Slovakia’s population would begin to rapidly increase in the years following the Second World War, however, as the country would experience both a baby boom and large-scale modernization and industrialization as part of the Czechoslovak Socialist Republic. After slowing somewhat in the late 1960s, population growth would increase once more in the 1970s and 1980s, as Slovakia would become the first of the Soviet republics to begin the “normalization” process of reforms brought about by the Soviet perestroika (restructuring) movement. While population growth would largely flatline following the dissolution of the Soviet Union in 1991, unlike many former Soviet republics who saw their populations decline as net emigration rose, Slovakia’s population has managed to avoid declining, and in the 2010s, has even begun to rise again. As a result, in 2020, Slovakia is estimated to have a population of just under five and a half million.

In 1800, the region of present-day Peru had a population of approximately 1.3 million people. Growth was slow at the beginning of the 19 th century. However, following Peru’s breakaway from the Spanish empire in 1824, the population would begin to slowly increase, and would nearly triple by the turn of the 20th century to approximately 3.7 million. This growth would expand exponentially in the mid-1900s, particularly during the global baby boom in the 1950s and 1960s, as an increase in fertility combined with decreases in child mortality led to rapid growth of the increasingly urbanizing population. This growth would slow somewhat between 1995 and 2013, a slowdown in part attributed to a large-scale expansion of family planning services in the country. However, the last decade has seen an increase in the rate of population growth in Peru, as the country has been one of the main destinations for Venezuelan refugees; with over 600,000 refugees residing in the country as of 2019. As a result, by 2020, almost 33 million people are estimated to live in the country.

Between 1800 and 2021, the total population of each continent experienced consistent growth, however as growth rates varied by region, population distribution has fluctuated. In the early 19th century, almost 70 percent of the world's population lived in Asia, while fewer than 10 percent lived in Africa. By the end of this century, it is believed that Asia's share will fall to roughly 45 percent, while Africa's will be on course to reach 40 percent. 19th and 20th centuries Fewer than 2.5 percent of the world's population lived in the Americas in 1800, however the demographic transition, along with waves of migration, would see this share rise to almost 10 percent a century later, peaking at almost 14 percent in the 1960s. Europe's share of the global population also grew in the 19th century, to roughly a quarter in 1900, but fell thereafter and saw the largest relative decline during the 20th century. Asia, which has consistently been the world's most populous continent, saw its population share drop by the mid-1900s, but it has been around 60 percent since the 1970s. It is important to note that the world population has grown from approximately one to eight billion people between 1800 and the 2020s, and that declines in population distribution before 2020 have resulted from different growth rates across the continents. 21st century Africa's population share remained fairly constant throughout this time, fluctuating between 7.5 and 10 percent until the late-1900s, but it is set to see the largest change over the 21st century. As Europe's total population is now falling, and it is estimated that the total populations of Asia and the Americas will fall by the 2050s and 2070s respectively, rapid population growth in Africa will see a significant shift in population distribution. Africa's population is predicted to grow from 1.3 to 3.9 billion people over the next eight decades, and its share of the total population will rise to almost 40 percent. The only other continent whose population will still be growing at this time will be Oceania, although its share of the total population has never been more than 0.7 percent.

In 1800, the population of the territory that makes up present-day Thailand was approximately 4.7 million people. As part of the kingdom of Siam, the population of Thailand would grow gradually through the 19 th century, with much of the population growth being driven by Chinese emigration from southern Qing China into Siam, in search of work and refuge from instability in their home country. This migrant influx would continue throughout the century, with estimates suggesting that the Chinese population in Siam grew from 230,000 in 1825, to over 792,000 in 1910; by 1932, over 12 percent of the population in modern-day Thailand was ethnically Chinese. Migration from China would see another surge under the reign of Vajiravudh, as the "Warlord era" in China, after the fall of the Qing dynasty, would see entire families of Chinese immigrants arriving in Thailand. While immigration would slow in later years, Chinese-Thai would remain a significant demographic in Thailand’s population, both as one of the largest overseas Chinese populations, and accounting for an estimated 11-14 percent of the total Thailand population in 2012.

Population growth would slow somewhat in the 1930s, as several rebellions and coups, paired with a rise in anti-Chinese sentiment in the country, would result in a sharp decline in immigration to the country. In the years following the Second World War, the population of Thailand would begin to grow rapidly, following a wave of urbanization and a significant increase in standard of living throughout the country. As a result, the population of Thailand would rise from approximately 20 million in 1950, to just under 63 million by the turn of the century just 50 years later. This population growth would slow somewhat as the country would continue to modernize in the 2000s, and in 2020, it is estimated that just under 70 million people live in Thailand.

In 1800, the population of Indonesia was estimated to be approximately 16 million. The population of the island nation would grow steadily over the course of the 19th century, as the Dutch colonial administration launched several initiatives to modernize the region. After reaching 38 million people in 1900, the population of Indonesia would continue to grow until the 1940’s, when the Japanese occupation of the country would see between four to ten million Indonesians moved away from the island nation to be made to work on Japanese military projects, and in combination with wartime famine, this would result in the death or displacement of up to four million Indonesians by the end of the Japanese occupation in 1945. Despite this, Indonesia's population continued to grow throughout these years.

Following the Second World War, Indonesia claimed its independence from the Netherlands, and achieved this in 1949. In the second half of the 20thcentury, the population would continue to grow exponentially in size through the remainder of the 20th century, although the growth rate would slow somewhat in the 1980s, the result of a decline in fertility rate throughout the country which some studies suggest may be attributed to improved access to birth control and improved mass education. In 2020, Indonesia is estimated to have just over 273.5 million people living within its borders, making it the fourth most populous country in the world (behind the U.S. and above Pakistan).

In 1800, the population of the region that makes up present-day Ecuador was approximately half a million people. This figure would begin to grow following Ecuador’s breakaway from the Spanish empire, first into the state of Gran Colombia in 1822, and then as its own fully independent republic in 1830. The Ecuadorian population would grow slowly but steadily throughout the 19th century, and by 1900, the country would have just under one and a half million people. Beginning in the 1930s, however, population growth would begin to increase more and more rapidly, as reforms and modernization programs begun under José María Velasco Ibarra would allow for an increasingly large population to be supported. As a result, Ecuador’s population would triple from a little over two million in 1930, to over six million in 1970. This growth would remain steady well into the 21st century, and in 2020, Ecuador is estimated to have a population of approximately 17.6 million.

Throughout the 19th century, what we know today as Poland was not a united, independent country; apart from a brief period during the Napoleonic Wars, Polish land was split between the Austro-Hungarian, Prussian (later German) and Russian empires. During the 1800s, the population of Poland grew steadily, from approximately nine million people in 1800 to almost 25 million in 1900; throughout this time, the Polish people and their culture were oppressed by their respective rulers, and cultural suppression intensified following a number of uprisings in the various territories. Following the outbreak of the First World War, it is estimated that almost 3.4 million men from Poland served in the Austro-Hungarian, German and Russian armies, with a further 300,000 drafted for forced labor by the German authorities. Several hundred thousand were forcibly resettled in the region during the course of the war, as Poland was one of the most active areas of the conflict. For these reasons, among others, it is difficult to assess the extent of Poland's military and civilian fatalities during the war, with most reliable estimates somewhere between 640,000 and 1.1 million deaths. In the context of present-day Poland, it is estimated that the population fell by two million people in the 1910s, although some of this was also due to the Spanish Flu pandemic that followed in the wake of the war.

Poland 1918-1945

After more than a century of foreign rule, an independent Polish state was established by the Allied Powers in 1918, although it's borders were considerably different to today's, and were extended by a number of additional conflicts. The most significant of these border conflicts was the Polish-Soviet War in 1919-1920, which saw well over 100,000 deaths, and victory helped Poland to emerge as the Soviet Union's largest political and military rival in Eastern Europe during the inter-war period. Economically, Poland struggled to compete with Europe's other powers during this time, due to its lack of industrialization and infrastructure, and the global Great Depression of the 1930s exacerbated this further. Political corruption and instability was also rife in these two decades, and Poland's leadership failed to prepare the nation for the Second World War. Poland had prioritized its eastern defenses, and some had assumed that Germany's Nazi regime would see Poland as an ally due to their shared rivalry with the Soviet Union, but this was not the case. Germany invaded Poland on September 1, 1939, in the first act of the War, and the Soviet Union launched a counter invasion on September 17; Germany and the Soviet Union had secretly agreed to do this with the Molotov-Ribbentrop Pact in August, and had succeeded in taking the country by September's end. When Germany launched its invasion of the Soviet Union in 1941 it took complete control of Poland, which continued to be the staging ground for much of the fighting between these nations. It has proven difficult to calculate the total number of Polish fatalities during the war, for a variety of reasons, however most historians have come to believe that the figure is around six million fatalities, which equated to almost one fifth of the entire pre-war population; the total population dropped by four million throughout the 1940s. The majority of these deaths took place during the Holocaust, which saw the Nazi regime commit an ethnic genocide of up to three million Polish Jews, and as many as 2.8 million non-Jewish Poles; these figures do not include the large number of victims from other countries who died after being forcefully relocated to concentration camps in Poland.

Post-war Poland

The immediate aftermath of the war was also extremely unorganized and chaotic, as millions were forcefully relocated from or to the region, in an attempt to create an ethnically homogenized state, and thousands were executed during this process. A communist government was quickly established by the Soviet Union, and socialist social and economic policies were gradually implemented over the next decade, as well as the rebuilding, modernization and education of the country. In the next few decades, particularly in the 1980s, the Catholic Church, student groups and trade unions (as part of the Solidarity movement) gradually began to challenge the government, weakening the communist party's control over the nation (although it did impose martial law and imprison political opponent throughout the early-1980s). Increasing civil unrest and the weakening of Soviet influence saw communism in Poland come to an end in the elections of 1989. Throughout the 1990s, Poland's population growth stagnated at around 38.5 million people, before gradually decreasing since the turn of the millennium, to 37.8 million people in 2020. This decline was mostly due to a negative migration rate, as Polish workers could now travel more freely to Western Europea...

In 1800, the population of Spain was approximately 14.7 million. This figure would rise consistently throughout the 19th century, and early 20th century. The population growth rate was set to increase in the mid-1900s, but this was interrupted by the Spanish Civil War, which would claim around half a million lives between 1936 and 1939. In spite of the war, the Spanish population continued to grow throughout these years, and reached 28 million by the middle of the century. Between the 1950s and 1970s, Spain observed a significant increase in its population growth, facilitated by the baby boom that followed the Second World War (as in most of Western Europe) as well as general medical improvements and increased life expectancy.

Beginning in the 1980s, Spain would begin a demographic transition marked by a dramatic drop in the fertility rate of the country, resulting in the population only growing by two million between the mid-1980s and 2000 (compared to an increase of two million every five or six years beforehand). There was a sharp rise in Spain’s population from 2000 to 2008, as strong economic growth would be accompanied by a dramatic surge in immigration to the country. This would plateau at just over 46 million in 2008 however, as the Great Recession took its toll on the country’s economy, and in 2020, Spain is estimated to have a population of approximately 46.8 million, which is the sixth-largest in Europe.

The population in Chile at the beginning of the 19th century was approximately 770,000, and growth was relatively low until Chile’s successful breakaway from the Spanish empire in the 1830s, when it became an independent republic. The population of the country would proceed to triple to over three million by the end of the century and would continue to grow rapidly throughout the 20th and into the 21st century. This rate of increase has been falling slowly since 1990, however, as a result of declining birth rates in the country, and in 2020, Chile is estimated to have a population of just over 19 million.

In 1800, the region of Germany was not a single, unified nation, but a collection of decentralized, independent states, bound together as part of the Holy Roman Empire. This empire was dissolved, however, in 1806, during the Revolutionary and Napoleonic eras in Europe, and the German Confederation was established in 1815. Napoleonic reforms led to the abolition of serfdom, extension of voting rights to property-owners, and an overall increase in living standards. The population grew throughout the remainder of the century, as improvements in sanitation and medicine (namely, mandatory vaccination policies) saw child mortality rates fall in later decades. As Germany industrialized and the economy grew, so too did the argument for nationhood; calls for pan-Germanism (the unification of all German-speaking lands) grew more popular among the lower classes in the mid-1800s, especially following the revolutions of 1948-49. In contrast, industrialization and poor harvests also saw high unemployment in rural regions, which led to waves of mass migration, particularly to the U.S.. In 1886, the Austro-Prussian War united northern Germany under a new Confederation, while the remaining German states (excluding Austria and Switzerland) joined following the Franco-Prussian War in 1871; this established the German Empire, under the Prussian leadership of Emperor Wilhelm I and Chancellor Otto von Bismarck. 1871 to 1945 - Unification to the Second World War The first decades of unification saw Germany rise to become one of Europe's strongest and most advanced nations, and challenge other world powers on an international scale, establishing colonies in Africa and the Pacific. These endeavors were cut short, however, when the Austro-Hungarian heir apparent was assassinated in Sarajevo; Germany promised a "blank check" of support for Austria's retaliation, who subsequently declared war on Serbia and set the First World War in motion. Viewed as the strongest of the Central Powers, Germany mobilized over 11 million men throughout the war, and its army fought in all theaters. As the war progressed, both the military and civilian populations grew increasingly weakened due to malnutrition, as Germany's resources became stretched. By the war's end in 1918, Germany suffered over 2 million civilian and military deaths due to conflict, and several hundred thousand more during the accompanying influenza pandemic. Mass displacement and the restructuring of Europe's borders through the Treaty of Versailles saw the population drop by several million more.

Reparations and economic mismanagement also financially crippled Germany and led to bitter indignation among many Germans in the interwar period; something that was exploited by Adolf Hitler on his rise to power. Reckless printing of money caused hyperinflation in 1923, when the currency became so worthless that basic items were priced at trillions of Marks; the introduction of the Rentenmark then stabilized the economy before the Great Depression of 1929 sent it back into dramatic decline. When Hitler became Chancellor of Germany in 1933, the Nazi government disregarded the Treaty of Versailles' restrictions and Germany rose once more to become an emerging superpower. Hitler's desire for territorial expansion into eastern Europe and the creation of an ethnically-homogenous German empire then led to the invasion of Poland in 1939, which is considered the beginning of the Second World War in Europe. Again, almost every aspect of German life contributed to the war effort, and more than 13 million men were mobilized. After six years of war, and over seven million German deaths, the Axis powers were defeated and Germany was divided into four zones administered by France, the Soviet Union, the UK, and the U.S.. Mass displacement, shifting borders, and the relocation of peoples based on ethnicity also greatly affected the population during this time. 1945 to 2020 - Partition and Reunification In the late 1940s, cold war tensions led to two distinct states emerging in Germany; the Soviet-controlled east became the communist German Democratic Republic (DDR), and the three western zones merged to form the democratic Federal Republic of Germany. Additionally, Berlin was split in a similar fashion, although its location deep inside DDR territory created series of problems and opportunities for the those on either side. Life quickly changed depending on which side of the border one lived. Within a decade, rapid economic recovery saw West Germany become western Europe's strongest economy and a key international player. In the east, living standards were much lower, although unemployment was almost non-existent; internationally, East Germany was the strongest economy in the Eastern Bloc (after the USSR), though it eventually fell behind the West by the 1970s. The restriction of movement between the two states also led to labor shortages in t...

In 1800, the population of the area of modern-day Lithuania was estimated to be just under 780,000. Lithuania’s rate of population growth would remain largely unchanged in the 19th century, as the Russian Empire would slowly but gradually develop its border regions. While large numbers of Lithuanians would emigrate west-ward (largely to the United States) between 1867 and 1868 after a famine in the country, growth would remain largely uninterrupted until the beginning of the First World War in 1912, which would see Lithuania, like much of the Baltic region, devastated as the battleground between the German and Russian Empires. As the conflict spread, those who were not made to evacuate by orders from the Russian government would face economic turmoil under German occupation, and as a result, Lithuania’s population would fall from just under 2.9 million in 1910, to under 2.3 million by 1920.

While Lithuania’s population would start to grow once more following the end of the First World War, this growth would be short-lived, as economic turmoil from the Great Depression, and later occupation and campaigns of mass extermination in the Second World War, most notably the extermination of 95 to 97 percent of the country’s Jewish population in the Holocaust, would cause Lithuania’s population growth to stagnate throughout the 1930s and 1940s. In the years following the end of the Second World War, Lithuania’s population would steadily climb, as industrialization by the Soviet Union would lead to improved economic growth and access to health, and campaigns of mass immunization and vaccination would lead to a sharp decline in child mortality. As a result, by the 1990s, Lithuania would have a population of over 3.7 million. However, Lithuania’s population would rapidly decline in the years following the dissolution of the Soviet Union in 1991, as economic crises and mass emigration from the country, paired with sharp declines in fertility, would result in a dramatic reduction in population. As a result, in 2020, Lithuania is estimated to have a population of just over 2.7 million.

In 1800, the population of the region making up present-day Croatia was just over 1.2 million. Croatia's population grew relatively consistently throughout the 19th and early 20th centuries, despite the region suffering around 200,000 fatalities in each of the World Wars. The lack of clearly defined boundaries, mass displacement and general disorganization have made it very difficult for historians to estimate the total number of fatalities suffered by Croatia and by ethnic Croats in this time; additionally, the various ethnic groups within Yugoslavia at the time committed a number of atrocities against one another, which has exacerbated this.

In spite of these events, the population of Croatia would continue to grow steadily until the early 1990s, when it was one of six parts of the Socialist Federative Republic of Yugoslavia. In the wake of communism's demise in Southern Europe in the late 20th century, Croatia claimed its sovereignty in 1991, which set in motion the Croatian War of Independence with Serbia. War was waged for four years, and saw the deaths of more than 20,000 people, while several hundred thousand were displaced. In the quarter century since the war's end, Croatia has emerged as a high-income, developing country, with a booming tourism and hospitality industry. However the population has continued to drop as a result of declining birth rates, and large-scale economic migration (particularly influenced by the financial crisis of 2008 and Croatia's accession to the European Union in 2013).

In 1800, the region of present-day Syria had a population of approximately 1.25 million people. Growth was relatively slow during the 19th century, and the population reached just over two million by the time of the First World War in 1914. However, population would begin to grow more rapidly following the beginning of French occupation in 1920, and by the time Syria achieved independence from France in 1946, the population would be just over 3.2 million. Following the country’s independence, Syria would begin experiencing exponential growth, the result of significant economic growth from the country’s growing petroleum exports.

However, the 21st century would see a sharp reversal of Syria’s exponential population growth, with the beginning of the Syrian Civil War after widespread anti-government protests in 2011. After peaking at 21.4 million people in 2010, Syria’s population would see a rapid decline during the civil war, as widespread conflict, massacres, and destruction would lead to significant fatalities and a mass exodus of refugees from the country, with several million migrating to neighboring Turkey, Lebanon, and Jordan, and another several hundred thousand ultimately migrating to the European Union. As a result, the population of the country has declined greatly, falling from over 21 million in 2010 to just under 17 million by 2018. However, as the fighting has gradually decreased in intensity and refugee rates have levelled off, the population of Syria has slowly began to grow again. In 2020, Syria is estimated to have a population of 17.5 million people.