Methodology & Sources
Every number on this site comes from a public record and is computed the same way for everyone, party-blind. Here is exactly how — and where each figure comes from.
Legitimacy
The share of eligible citizens — the citizen voting-age population (CVAP) of the district or state — who actively cast a vote for the current officeholder: winner's votes ÷ CVAP. It is not vote share (of ballots cast) and not turnout; it asks how much of the electorate that could vote actually chose this person. Almost no seat reaches half.
Sources: U.S. Census CVAP (eligible-voter denominator); MIT Election Lab / official returns (votes).
Competitiveness (margin)
The winner's margin over the runner-up as a share of votes cast: (winner − runner-up) ÷ total votes. A low margin is a genuine tossup; a high margin (up to an effectively unopposed 100 points) is a safe seat.
Source: MIT Election Lab / official returns.
Turnout
Total votes cast in the race ÷ CVAP — the share of eligible citizens who voted at all, for anyone.
Sources: Census CVAP; official returns.
Campaign money & outside money
Money raised is total campaign receipts (the better of the last two cycles, so a partial current cycle doesn't understate a big raiser). Outside money is independent expenditures — Super-PAC money spent supporting or opposing the member that never passes through their own committee, the post–Citizens United money. Both are federal-only and log-scaled per chamber on the map.
Party independence
Over the roll-call votes we sample, how often the member sided with the majority of their own party (excluding themselves from that majority). A low rate means they break ranks often. This is a recent-votes signal, not a career score, and it is only shown for members with enough classifiable votes; independents who caucus with a party are not scored.
Sources: House Clerk and Senate LIS roll-call records.
Rankings & percentiles
Rankings compare each entity against its own chamber (and, for scale-free measures like legitimacy and margin, against all of Congress). A percentile bar shows where a seat falls on the whole distribution rather than just a rank, so the comparison is honest in both directions.
Why state legislators show less
State legislatures don't publish roll-call, turnout or campaign-finance data in a single national feed the way Congress does. Until per-district CVAP and 50 states' finance systems are wired in, state pages lead with identity and committees and say plainly what isn't available yet.
Source: OpenStates (legislators, districts, committees).