Known as the Dillingham Commission, the U.S. Immigration Commission was a joint House-Senate Commission that produced a series of reports on immigration and immigrants between 1907 and 1911. The forty-one volume series includes a wealth of information on immigrant communities, statistics on immigration, immigrant workers in specific industries, children of immigrants in schools and immigration legislation. The Commission was created by anti-immigration forces in Congress and that is reflected in some volumes of the report, such as the "Dictionary of Races and Peoples" and in the recommendations to restrict immigration from southern and eastern Europe.
These sources include statistics on people living in the United States, or immigrating to the United States. Older immigration statistics can be found in the annual reports of the Immigration and Naturalization Services (or before 1933, the Bureau of Immigration). Copies of most of these can be found digitized in Hathi Trust or in print via SUMMIT.