Center for U.S.-Mexican Studies
A research center based at UC San Diego. Working papers are available in PDF format.

Department of Homeland Security: Immigration Data & Statistics
Immigration, naturalization and border apprehension statistics. Includes the Yearbook of Immigration Statistics in PDF format.

Immigration to the United States, 1789-1930
A digital collection from Harvard University Library. The collection includes books, pamphlets, photographs and archival materials.

LANIC: Immigration & Migration
An excellent collection of links to country and regional resources, academic research resources, government agencies and organizations maintained by the Latin American Network Information Center at University of Texas at Austin.

Mexican Migration Project
A research collaboration between the Office of Population Research at Princeton University and Depto. de Estudios Sobre Movimientos Sociales (DESMOS) at Universidad de Guadalajara. Links to data and publications available for purchase and free for download.

New Immigrant Survey
An ongoing research project based at Princeton focusing on new legal immigrants to the U.S. and their children.  The website provides access to data and research papers of the project.  Registration is required.

Pew Hispanic Center: Immigration
Data and public opinion surveys.

U.S. Census Bureau: Migration/Geographic Mobility
Both current and historical statistics relating to immigration, refugees and foreign born population.