The Constitution of the United States of America: Analysis and Interpretation (popularly known as the Constitution Annotated) contains legal analysis and interpretation of the United States Constitution, based primarily on Supreme Court case law. (From Congress.gov.)
An annotated version of The U.S. Constitution containing legal analysis based on Supreme Court decisions with links to case summaries that include lists of Supreme Court decision in which they are cited. (From the Legal Information Institute at Cornell Law School.)
Almanac of American Politics 2018
Analysis and profiles of every congressional district, state, governor and member of Congress. Includes demographic information for every state and district, information from the Census Bureau's American Community Survey. Campaign finance data on spending by all Senate and House members in the most recent election, and more. Library holdings:
The Almanac of Women and Minorities in American Politics 2002 by Mart Martin
Reference to all women, African-Americans, Hispanics, Asian-Americans, Native minorities, gays, and lesbians who have served in state or national elected positions, with additional information on local elected positions.