The American Religion Data Archive (ARDA) is an open source website that holds over 200 surveys on religion, including general population surveys, surveys of selected religious groups, surveys of religious professionals, and aggregate church, congregational and denominational data.

This survey of U.S. households has been performed nearly annually since 1972 by the National Opinion Research Center (NORC). The survey is unique in that it is collected for general secondary use by researchers and is intended for use by the social science community. The link above is to the GSS at ICSPR where you can find very user-friendly online documentation.

Consists of four large, nationally representative surveys that track changes in religious loyalties of the U.S. adult population, ranging from 1990 to 2014.

Religion statistics in various categories.

The Pew Research Center conducts surveys, demographic analyses and other social science research on important aspects of religion and public life in the U.S. and around the world.

An extensive new survey by the Pew Forum on Religion & Public Life details statistics on religion in America and explores the shifts taking place in the U.S. religious landscape. Based on interviews with more than 35,000 Americans age 18 and older, the U.S. Religious Landscape Survey finds that religious affiliation in the U.S. is both very diverse and extremely fluid.

Survey of voting behavior in the United States, conducted biennially since 1948. Basic questions on religious identification and attendance at religious services have been asked throughout the time series but the religion module was substantially widened and improved starting in 1990, making possible richer analyses of how religion affects political attitudes and behavior. Contains links to download all the data.

This is a repository for demographic and other quantitative social scientific surveys about Jews in the United States, Canada, and the world. It archives the National Jewish Population Surveys as well as a number of community surveys, and includes American Jewish Yearbook back to 1899.

Search for religion data at the ICPSR Data Archive, the world's largest archive of social science data. election data, opinion polls, and more.

A nationally representative study of congregations carried out via interviews with congregational informants, mostly clergy. Conducted in conjunction with the 1998 General Social Survey (GSS). Respondents reported on a wide variety of congregational activities. A sample size of 1236.

PRRI’s research explores and illuminates America’s changing cultural, religious, and political landscape. PRRI’s mission is to help journalists, scholars, pundits, thought leaders, clergy, and the general public better understand debates on public policy issues, and the important cultural and religious dynamics shaping American society and politics.

The government collects information about livestock, sales, and related information. Look here, also, for immigration information.

Features government data pertaining to jobs, skills, and education across US states.

The U.S. government's open data portal. Limit by file type to locate textual data resources. Files are accessible as XML files, PDFs, HTML files, or TXT files.