With Texas Gov. Rick Perry sending National Guard troops to the border, look back at the tumultuous history of immigation in America.
1795 -- The Naturalization Act restricts U.S. citizenship to "free white persons" who live in America for at least five years and renounce their allegiance to their former country.
National Archives and Records Administration
J.K. Nakata/United States Geological Survey
Akron Public Schools/CNN
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