RealClearPolitics provides well-respected polling data, known as the RCP Average, aggregated news stories, and information on various political topics.
This site works to reduce the level of deception and confusion in U.S. politics by monitoring the factual accuracy of what is said in TV ads, debates, speeches, interviews and news releases; a project of the Annenberg Public Policy Center of the University of Pennsylvania.
APSA brings together political scientists from all fields of inquiry, to deepen understanding of politics, democracy, and citizenship throughout the world.
The U.S. Politics section of Pew Research Center's website has data, analysis, and survey reports. You can also check out other related sections such as Global Trends or Journalism & Media.
ANES produces high quality data from its own surveys on voting, public opinion, and political participation to serve the purposes of social scientists, teachers, students, policy makers.
Congress.gov is the official website for U.S. federal legislative information. The site provides access to accurate, timely, and complete legislative information for Members of Congress, legislative agencies, and the public.
The Government Manual provides comprehensive information on the legislative, judicial, and executive branches. It also includes information on quasi-official agencies, international organizations with U.S. membership, and Federal boards, commissions, and committees.