Lists major releases of historical census data online for the country, states, cities, metro areas, etc. Very useful starting point for historical census questions.

Concentrating heavily on the 19th century, Immigration to the United States, 1789-1930, includes approximately 1,800 books and pamphlets as well as 6,000 photographs, 200 maps, and 13,000 pages from manuscript and archival collections. By incorporating diaries, biographies, and other writings capturing diverse experiences, the collected material provides a window into the lives of ordinary immigrants

Instructions given to census takers from 1850-2000. It's important to note that census takers filled out the forms until 1960, when self-enumeration began in part.

The following reports are published from the 2002 Economic Census, Company Statistics (CS)
Series, Survey of Business Owners, and include totals for all U.S. businesses based on the 2002
Economic Census and estimates of business ownership by gender, Hispanic or Latino origin, and
race based on the 2002 SBO. Estimates for equally male-/female-owned firms and publicly held
companies and other businesses whose ownership cannot be classified by gender, Hispanic or
Latino origin, and race are tabulated and published separately.

County maps of the US by religious affiliation.

From Moving Ideas.org, this site provides access to organizations and Think Tanks along the liberal/progressive side of issues.

 

University of Michigan guide to Think Tank sources.

A guide to the literature on Think Tanks from the Columbia University Library.

From the Heritage Foundation, this site provides great access to leading thinkers and Think Tanks along the conservative side of all issues.

From their website:
"Policy Experts is your single-source directory for locating knowledgeable authorities and leading policy institutes actively involved in a broad range of public policy issues, both domestic and foreign. Journalists, researchers, public officials and conference planners find it to be an indispensable guide for locating the right expert at a moment's notice."

Links and descriptions to the major U.S. political think tanks. The descriptions are generally from the think tanks mission.

Includes funding, staffing, mission statements, areas of research, officers, researchers, major findings, periodicals and library holdings, and affiliation with othe rinstitues.

This is the 29^th annual Department of Defense (DoD) report on social representation in the U.S. Military Services, including the Coast Guard. The seven chapters and accompanying technical appendices provide data and comments on demographic, educational, and aptitude characteristics of applicants, new recruits, and enlisted and officer members of the Active and Reserve Components. Except where otherwise noted, data are provided by Defense Manpower Data Center (DMDC). Due to differences in data flow and definitions, values provided will not always match official figures reported by the Directorate for Information Operations and Reports, other Department of Defense agencies, or military services. This report covers fiscal year (FY) 2002, from October 1, 2001, to September 30, 2002