Immigrants composed 13.6 percent of the U.S. population in 2021, or about 45 million people out of a total of more than 332 million, according to the U.S. Census Bureau. Together, immigrants and their U.S.-born children make up about 27 percent of U.S. inhabitants per the 2022 Current Population Survey, and the Census Bureau has predicted that the total number of immigrants living in the United States will reach 65 million by 2050. Though the share of the population that is foreign born has steadily risen since 1970, when there were fewer than 10 million immigrants in the country, today’s figure is still slightly below the record high of 14.8 percent in 1890. 

As of 2021, Mexico was the most common country of origin for U.S. immigrants, with Mexicans constituting 24 percent of the total immigrant population. Other major countries of origin include India (6 percent), China (5 percent), and the Philippines (4 percent).

Undocumented immigration. The undocumented population was estimated to be about eleven million people in 2019; more recent data is not yet available due to difficulty collecting information amid the COVID-19 pandemic. This total represents a slight decrease from the population’s peak before the 2008 economic crisis [PDF], which led some migrants to return to their home countries and discouraged others from coming to the United States. In fiscal year 2022 (FY2022), Customs and Border Protection (CBP) apprehended more than 2.3 million people trying to illegally cross the southern U.S. border, a record high.

Until 2013, almost all of those trying to cross the U.S.-Mexico border were Mexican citizens, and most were individuals seeking work. Between 2013 and 2021, most immigrants came from Asia, particularly China and India. Mexico has since regained its status as the top country of origin, and Central Americans have made up an increasingly larger share of migrants at the southern U.S. border. Generally, they are coming not for work but to make asylum claims, and many of them are unaccompanied children. Some of these immigrants have different legal rights from Mexican nationals in the United States: Under a 2008 anti–human trafficking law, unaccompanied minors from noncontiguous countries have a right to a hearing before being deported to their home countries. The increase in Central American migration has strained the U.S. immigration system. At the end of FY2022, there were 1.9 million cases pending in immigration courts, and by mid-2023, that number had grown to more than 2 million, the most on record.