Data.gov
Data.gov is the federal government's open data site. Launched by the U.S. General Services Administration (GSA) in May 2009 with a modest 47 datasets, Data.gov has grown to over 200,000 datasets from hundreds of data sources including federal agencies, states, counties, and cities. Data.gov provides easy access to government datasets covering a wide range of topics—everything from weather, demographics, health, education, housing, and agriculture, and more.