MapLight's website combines three data sets:
- Contributions: Campaign contributions given to each member of Congress. (Source: Center for Responsive Politics)
- Support/opposition: Which interest groups and companies support and oppose key bills. (Source: MapLight research team)
MapLight also makes available for free, public use our Federal Money and Politics Data Set, an easy-to-access, downloadable database of MapLight-enhanced Federal Elections Commission (FEC) campaign finance data.