Sources
Behind the Ballot is non-partisan: every published figure traces to a public data source with a freshness floor. If data goes stale past its floor, the figure is flagged rather than shown silently. This is the data contract.
| Data | Provider | License | Cadence | Freshness floor | Used by |
|---|---|---|---|---|---|
| Campaign finance | OpenFEC + FEC bulk | US public domain | weekly | 14 days | Finance, tracker |
| Polls | 538 polls CSV | 538 terms (attributed) | daily | 3 days | Polling, forecast |
| Pollster ratings | 538 pollster ratings | 538 terms (attributed) | weekly | 30 days | Polling |
| Demographics | US Census ACS | US public domain | yearly | 400 days | Demographics, forecast |
| District geography | Census TIGER/Line | US public domain | yearly + court orders | event-driven | Gerrymander, maps |
| Address lookup | Census Geocoder | US public domain | on request (cached) | 30-day cache | Find my district |
| Members of Congress | congress-legislators + Congress.gov | CC0 / US public domain | weekly | 14 days | Members, caucus |
| Roll-call votes | Congress.gov + GovTrack | US public domain / GovTrack terms | daily (in session) | 7 days | Member analytics |
| Ideology | Voteview DW-NOMINATE | Academic, free (attributed) | per Congress | event-driven | Member analytics |
Government sources (FEC, Census, Congress.gov, Geocoder, TIGER) are US public domain. Wikipedia content is CC BY-SA; Voteview and GovTrack are credited per their terms.