ProPublica Data Store

https://www.propublica.org/datastore

ProPublica provides free access to the raw data behind their investigative journalism, as well as premium data products and custom data services.

Resources include a variety of datasets about Health, Criminal Justice, Education, Politics, Business, Transportation, Military, Environment, Finance, or Religion. They also offer three APIs providing access to datastreams on campaign finance, nonprofit organizations, and political ad buys.