In the nineteenth and twentieth centuries, the majority of documented migration to the United States of American came from European countries. Between 1820 and 1957, of the approximate 41 million migrants to the US, over 34 million of these came from Europe. The most commonly documented countries of origin during this time were Germany (6.6 million), Italy (4.9 million), Ireland (4.6 million), Great Britain (4.5 million), and Russia (3.4 million). The first wave of mass migration came in the 1850s, as the Great famine crippled Ireland's population, and many in rural areas of mainland Europe struggled to adapt to industrialization, and economic opportunities attracted many in the 1870s, following the American Civil War. The 1880s saw another wave, as steam powered ships and lower fares made trans-Atlantic journeys much more affordable. The first wave of mass migration from Eastern and Southern Europe also arrived at this time, as industrialization and agricultural advancements led to high unemployment in these regions.

The majority of migrants to the United States settled in major urban centers, which allowed the expansion of industry, leading to the United States' emergence as one of the leading global economies at the turn of the twentieth century. The largest wave of migration to the United states during this period came in the first fifteen years of the 1900s. The influx of migrants from Northern and Western Europe had now been replaced by an influx from Eastern and Southern Europe (although migration from the British Isles was still quite high during this time). European migration fell to it's lowest levels in eighty years during the First World War, before fluctuating again in the interwar period, due to the Great Depression. As the twentieth century progressed, the continent with the highest levels of migration to the US gradually changed from Europe to Latin America, as economic opportunities in Western Europe improved, and the US' relationship with the Soviet Union and other Eastern, communist states became complicated.

Between 1820 and 1957, approximately 3.8 million people migrated from Eastern Europe and Russia (which officially became the Soviet Union in 1922) to the United States. Although migration from Western Europe to the US had already increased significantly in the early 1800s, it was not until the 1870s that Eastern Europeans began to migrate in mass. The period with the highest rate of migration was between the turn of the twentieth century and the Russian Revolution, before it dropped drastically, and despite a small resurgence in the early 1920s, the numbers from both regions remained below one thousand migrants per year from before the Second World War and well into the Cold War.

Between 1500 and 1820, an estimated 2.58 million Europeans migrated to the Americas, namely from the British Isles, Portugal, Spain, France and Germany. Until the mid-1600s, the majority of European migrants were from the Iberian Peninsula, as Portugal and Spain had a 150 year head start over other European powers when building their overseas empires. However, by the end of the century, more settlers from the British Isles had emigrated to the New World than from Spain or Portugal; the majority of which migrated to British colonies in the Caribbean as indentured servants or prisoners. The 18th century also saw migrants from other European nations begin to migrate en masse, particularly those from France and the German states, although migration from the British Isles and Portugal remained at the highest levels.

In comparison to the almost 2.6 million Europeans migrants, it is estimated that over 8.6 million Africans were forced across the Atlantic during this time period, as part of the transatlantic slave trade. The first half of the 19th century saw the demise of the transatlantic slave trade, which was followed by an influx of white migration to the Americas from across Europe; this contributed heavily to reversing demographic trends and making those with African ancestry an ethnic minority in most American countries today.

In the past four centuries, the population of the Thirteen Colonies and United States of America has grown from a recorded 350 people around the Jamestown colony in Virginia in 1610, to an estimated 346 million in 2025. While the fertility rate has now dropped well below replacement level, and the population is on track to go into a natural decline in the 2040s, projected high net immigration rates mean the population will continue growing well into the next century, crossing the 400 million mark in the 2070s. Indigenous population Early population figures for the Thirteen Colonies and United States come with certain caveats. Official records excluded the indigenous population, and they generally remained excluded until the late 1800s. In 1500, in the first decade of European colonization of the Americas, the native population living within the modern U.S. borders was believed to be around 1.9 million people. The spread of Old World diseases, such as smallpox, measles, and influenza, to biologically defenseless populations in the New World then wreaked havoc across the continent, often wiping out large portions of the population in areas that had not yet made contact with Europeans. By the time of Jamestown's founding in 1607, it is believed the native population within current U.S. borders had dropped by almost 60 percent. As the U.S. expanded, indigenous populations were largely still excluded from population figures as they were driven westward, however taxpaying Natives were included in the census from 1870 to 1890, before all were included thereafter. It should be noted that estimates for indigenous populations in the Americas vary significantly by source and time period. Migration and expansion fuels population growth The arrival of European settlers and African slaves was the key driver of population growth in North America in the 17th century. Settlers from Britain were the dominant group in the Thirteen Colonies, before settlers from elsewhere in Europe, particularly Germany and Ireland, made a large impact in the mid-19th century. By the end of the 19th 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. It is also estimated that almost 400,000 African slaves were transported directly across the Atlantic to mainland North America between 1500 and 1866 (although the importation of slaves was abolished in 1808). Blacks made up a much larger share of the population before slavery's abolition. Twentieth and twenty-first century The U.S. population has grown steadily since 1900, reaching one hundred million in the 1910s, two hundred million in the 1960s, and three hundred million in 2007. Since WWII, the U.S. has established itself as the world's foremost superpower, with the world's largest economy, and most powerful military. This growth in prosperity has been accompanied by increases in living standards, particularly through medical advances, infrastructure improvements, clean water accessibility. These have all contributed to higher infant and child survival rates, as well as an increase in life expectancy (doubling from roughly 40 to 80 years in the past 150 years), which have also played a large part in population growth. As fertility rates decline and increases in life expectancy slows, migration remains the largest factor in population growth. Since the 1960s, Latin America has now become the most common origin for migrants in the U.S., while immigration rates from Asia have also increased significantly. It remains to be seen how immigration restrictions of the current administration affect long-term population projections for the United States.

Between 1820 and 1957, more than six million people emigrated from Germany to the United States. The period with the highest levels of migration came during the 1850s and the 1880s, and over 250 thousand documented migrants came to the US from Germany in 1882 alone. The reasons for these mass migrations were not linked to individual events, but were because of the improved access to trans-Atlantic travel, poor economic opportunities at home (particularly for farmers, who struggled with the rapid industrialization of Germany), and to escape religious persecution in Europe. The periods with the lowest levels of migration from Germany were between 1915 and 1945, and were likely caused by the First and Second World Wars, and also the Great Depression.

It is presumed that the first humans migrated from Siberia to North America approximately twelve thousand years ago, where they then moved southwards to warmer lands. It was not until many centuries later that humans returned to the north and began to settle regions that are now part of Canada. Despite a few short-lived Viking settlements on Newfoundland around the turn of the first millennium CE, the Italian explorer Giovanni Caboto (John Cabot), became the first European to explore the coast of North America in the late 1400s. The French and British crowns both made claims to areas of Canada throughout the sixteenth century, but real colonization and settlement did not begin until the early seventeenth century. Over the next 150 years, France and Britain competed to take control of the booming fur and fishing trade, and to expand their overseas empires. In the Seven Year's War, Britain eventually defeated the French colonists in North America, through superior numbers and a stronger agriculture resources in the southern colonies, and the outcome of the war saw France cede practically all of it's colonies in North America to the British.

Increased migration and declining native populations

The early 1800s saw a large influx of migrants into Canada, with the Irish Potato Famine bringing the first wave of mass-migration to the country, with further migration coming from Scandinavia and Northern Europe. It is estimated that the region received just shy of one million migrants from the British Isles alone, between 1815 and 1850, which helped the population grow to 2.5 million in the mid-1800s and 5.5 million in 1900. It is also estimated that infectious diseases killed around 25 to 33 percent of all Europeans who migrated to Canada before 1891, and around a third of the Canadian population is estimated to have emigrated southwards to the United States in the 1871-1896 period. From the time of European colonization until the mid-nineteenth century, the native population of Canada dropped from roughly 500,000 (some estimates put it as high as two million) to just over 100,000; this was due to a mixture of disease, starvation and warfare, instigated by European migration to the region. The native population was generally segregated and oppressed until the second half of the 1900s; Native Canadians were given the vote in 1960, and, despite their complicated and difficult history, the Canadian government has made significant progress in trying to include indigenous cultures in the country's national identity in recent years. As of 2020, Indigenous Canadians make up more than five percent of the total Canadian population, and a higher birth rate means that this share of the population is expected to grow in the coming decades.

Independence and modern Canada

Canadian independence was finally acknowledged in 1931 by the Statute of Westminster, putting it on equal terms with the United Kingdom within the Commonwealth; virtually granting independence and sovereignty until the Canada Act of 1982 formalized it. Over the past century, Canada has had a relatively stable political system and economy (although it was hit particularly badly by the Wall Street Crash of 1929). Canada entered the First World War with Britain, and as an independent Allied Power in the Second World War; Canadian forces played pivotal roles in a number of campaigns, notably Canada's Hundred Days in WWI, and the country lost more than 100,000 men across both conflicts. The economy boomed in the aftermath of the Second World War, and a stream of socially democratic programs such as universal health care and the Canadian pension plan were introduced, which contributed to a rise in the standard of living. The post war period also saw various territories deciding to join Canada, with Newfoundland joining in 1949, and Nunavut in 1999. Today Canada is among the most highly ranked in countries in terms of civil liberties, quality of life and economic growth. It promotes and welcomes immigrants from all over the world and, as a result, it has one of the most ethnically diverse and multicultural populations of any country in the world. As of 2020, Canada's population stands at around 38 million people, and continues to grow due to high migration levels and life expectancy, and a steady birth rate.