Immigration to the United States Immigration to the United
States is a complex demographic phenomenon that has been a major
source of population growth and cultural change throughout much
of the history of the United States. The economic, social, and
political aspects of immigration have caused controversy
regarding ethnicity, economic benefits, jobs for non-immigrants,
settlement patterns, impact on upward social mobility, crime,
and voting behavior. In 2006 the United States accepted more
legal immigrants as permanent residents than all other countries
in the world combined. After ethnic quotas on immigration were
removed in 1965 the number of actual (first-generation)
immigrants living in the United States eventually quadrupled,
from 9.6 million in 1970 to about 38 million in 2007. Over one
million persons were naturalized as U.S. citizens in 2008. The
leading countries of origin of immigrants to the United States
were Mexico, India, the Philippines, and China. Nearly 14
million immigrants entered the Unit