From which country did most people immigrate to the U. S.?

Mexico is your answer

Naturalization ceremony at Oakton High School in Fairfax County, Virginia, December 2015.

Immigrants to the United States take the Oath of Allegiance at a naturalization ceremony at the Grand Canyon National Park in Arizona, September 2010.

Immigration to the United States is the international movement of non-U. S. nationals in order to reside permanently in the country.[1] Lawful Immigration has been a major source of population growth and cultural change throughout much of the U. S. history. Because the United States is a settler colonial society, all Americans, with the exception of the small percent of Native Americans, can trace their ancestry to immigrants from other nations around the world.

In absolute numbers, the United States has a larger immigrant population than any other country, with 47 million immigrants as of 2015.[2] This represents 19.1% of the 244 million international migrants worldwide, and 14.4% of the U. S. population. Some other countries have larger proportions of immigrants, such as Switzerland with 24.9% and Canada with 21.9%.[3][4]

According to the 2016 Yearbook of Immigration Statistics, the United States admitted 1.18 million legal immigrants in 2016.[5] Of these, 20% were family-sponsored, 47% were the immediate relatives of U. S. citizens, 12% were employment-based preferences, 4% were part of the Diversity Immigrant Visa program, and 13% were refugees and/or asylum seekers.[5] The remainder included small numbers from several other categories, including those who were granted the Special Immigrant Visa (SIV); persons admitted under the Nicaraguan and Central American Relief Act; children born subsequent to the issuance of a parent's visa; and certain parolees from the former Soviet Union, Cambodia, Laos, and Vietnam who were denied refugee status.[5]