Data source:

Our database includes records of how each member of Congress voted on every bill.

The official record of this information is published on the House and Senate websites shortly after each vote occurs. Our partner group “scrapes” these government websites, using computer software to automatically translate the voting lists on the government websites into a structured database form.

We receive this data from within a few minutes after the House and Senate websites publish each vote. MapLight typically displays each vote in Congress within 45 minutes of when the vote happens.

We currently include floor votes (when all House members or senators vote), but not committee votes. We include votes on amendments to bills, as well as votes on the bills themselves. Often votes on amendments are more interesting than votes on the final bill.