"Launched in 2013, the project provides estimates on the size and characteristics of the US unauthorized and naturalization-eligible populations at national, state and sub-state levels. The initiative offers this information through interactive data tools, tables, charts and groundbreaking reports." - from the web site.

From the Center for Research on the Epidemiology of Disasters.

No longer maintained as of 2018, this web site from the University of Oxford was a rich resource of forced migration research and documents for 16 years. Now partially archived and available via the Internet Archive.

Harmonized data from counter-trafficking organizations, provided by the Counter-Trafficking Data Collaborative.

International, open, comparable data on migration, provided by the International Organization for Migration in collaboration with several other international organizations.

Data on immigrants and refugees in U.S., Europe, and other countries.

A robust guide to migration data from the Bodleian Libraries at Oxford.

From the Center for International Development and Conflict Management. Free registration required.

Data on deaths along migratory routes collected by the International Organization for Migration.

Though the site does not have a devoted data section, there is a deep trove of research available here under "Research," "Publications," and "Policy & Impact."

U.S. Committee for Refugees and Immigrants, publishers of the World Refugee Survey.

Survey data and analysis on the population, health, and nutrition of women and children in 75+ developing countries, collected by the U.S. Agency for International Development (USAID).

Under the MEASURE CDC project, CDC assists countries throughout the world with developing, implementing, and analyzing of large national reproductive health surveys that provide high quality, population-based data about reproductive health indicators. Each country's needs guide the survey content.