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.

Approximately 41 million people immigrated to the United States of America between the years 1820 and 1957. During this time period, the United States expanded across North America, growing from 23 to 48 states, and the population grew from approximately 10 million people in 1820, to almost 180 million people by 1957. Economically, the U.S. developed from being an agriculturally focused economy in the 1820s, to having the highest GDP of any single country in the 1950s. Much of this expansion was due to the high numbers of agricultural workers who migrated from Europe, as technological advances in agriculture had lowered the labor demand. The majority of these migrants settled in urban centers, and this fueled the growth of the industrial sector.

American industrialization and European rural unemployment fuel migration The first major wave of migration came in the 1850s, and was fueled largely by Irish and German migrants, who were fleeing famine or agricultural depression at the time. The second boom came in the 1870s, as the country recovered from the American Civil War, and the Second Industrial Revolution took off. The final boom of the nineteenth century came in the 1880s, as poor harvests and industrialization in Europe led to mass emigration. Improvements in steam ship technology and lower fares led to increased migration from Eastern and Southern Europe at the turn of the century (particularly from Italy). War and depression reduces migration Migration to the U.S. peaked at the beginning of the 20th century, before it fluctuated greatly at the beginning of the 20th century. This was not only due to the disruptions to life in Europe caused by the world wars, but also the economic disruption of the Great Depression in the 1930s. The only period between 1914 and 1950 where migration was high was during the 1920s. However, the migration rate rose again in the late 1940s, particularly from Latin America and Asia. The historically high levels of migration from Europe has meant that the most common ethnicity in the U.S. has been non-Hispanic White since the early-colonial period, however increased migration from Latin America, Asia and Africa, and higher fertility rates among ethnic minorities, have seen the Whites' share of the total population fall in recent years (although it is still over three times larger than any other group.

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.

Over 1.2 million refugees from Ukraine due to the Russian invasion fled to Germany as of April 2025. Furthermore, the second-highest number was recorded in Poland. In total, around 5.1 million Ukrainian refugees were registered across Europe and 5.6 million worldwide as of May 2025. Most of them fled the country by crossing the border with Poland. Ukrainian refugees in Germany The first increases in the number of Ukrainian refugees in Germany were registered in March and April 2022. The figure exceeded one million refugees in September of that year. Germany had the highest monthly financial allowance for Ukrainians who fled the war compared to other European countries as of June 2022. Temporary protection for Ukrainian refugees in the EU European Union (EU) members implemented the Temporary Protection Directive (TPD), which guaranteed access to accommodation, welfare, and healthcare to refugees from Ukraine. People fleeing the war had a right to a residence permit in the EU, enter the labor market, and enroll children in educational institutions. The protection is granted until March 4, 2026, but it can be extended in the future depending on the situation in the country.