migration, with larger numbers of people heading north in the spring and summer and larger numbers of people headed south in the fall and winter. There has long been a seasonal pattern to Mexican-U.S. But a substantial number also travel back and forth across the border through the year, a pattern known as circular migration.
Many immigrants settle permanently and have children born in the United States. There is great variation in the patterns of immigration among the nation’s 12 million Mexican-born immigrants. 1 Most immigrants who leave Mexico come to the United States, and one-in-ten Mexican-born people currently lives in the U.S.
Mexico is the largest country of origin for immigrants in the United States, accounting for 29% of the foreign-born population in 2010.