Office of Immigration Statistics, U.S. Department of Homeland Security: Provides official statistics on US immigration and naturalization.
United Nations Statistics Division – International Migration: The UNSD is responsible at the international level for collecting and disseminating official national data on international migration. Topics include international migration flows, labor migration statistics, asylum seekers and refugees and more.
US Census Bureau – Foreign Born: Provides statistics on the foreign born population in the US.
World Bank Databases: provides access to a wide range of World Bank data including World Development Indicators,Global Bilateral Migration Database, Measuring Brain Drain by Gender,Migration and Remittances Factbook, and Panel Data on International Migration 1975-2000.
Syracuse University, Transactional Records Access Clearinghouse (TRAC), Immigration Project: Verifies the details of information from the government for accuracy and completeness.
Migration Policy Institute Data Hub: Maps, data, and data profiles related to migration.
ICPSR Inter-University Consortium for Political and Social Research
Immigration Data Hub: An independent, non-partisan think-tank in Washington DC.
MIPEX (Migrant Integration Policy Index) is an interactive tool providing integration policy data from 31 countries presented by the British Council and the Migration Policy Group.
OECD iLibrary: Offers online access to the many publications and databases, including an international migration statistics database, put out by the Organisation for Economic Co-operation and Development (OECD).
*Also see the Mannheim Eurobarometer Trend File and Eurobarometer Question Search, which allows you to find if and when a topic was covered. Also includes a topical guide. Data is available through ICPSR and GESIS-ZACAT which includes a large number of EuroBarometer surveys and others and allows online analysis as well as access to microdatafiles (free registration is required).