How American politics has shifted
Two of the three branches, on a shared timeline since 1946. Congress is measured by DW-NOMINATE — the standard left–right scale, built to be comparable across eras — and the Supreme Court by its conservative-vote share each term. Both come straight from the source records (Voteview and the Supreme Court Database); no modeling.
Congress pulled apart
The median Democrat and median Republican in each chamber. The two lines barely differed a generation ago and now sit far apart — the House party gap has widened from 0.50 to 0.93. That spreading is polarization.
House
Senate
The Court's center of gravity
The share of cases the majority decided in the conservative direction each term — the outcome that actually sets the law — with the share of individual justice-votes shown fainter for context. The Warren Court decided barely a third of cases conservatively in the 1960s; the Court has ruled right of even since the 1970s. Above the dashed line, the majority leaned conservative that term.
By issue area
The share of cases decided conservatively, one panel per issue area on a shared scale. They don't move together — the Court can swing right on criminal cases while holding steadier on economic ones. The bold line is a smoothed trend; the faint line is the noisier term-by-term outcome.
Criminal Procedure
Civil Rights
First Amendment
Economic Activity
Sources & caveats
Congress: Voteview DW-NOMINATE first-dimension party medians per Congress. SCOTUS: Supreme Court Database conservative-direction share of case decisions per term (1946–2023), with justice-vote share for context. The two use different scales and shouldn't be read off one axis — hence separate panels. DW-NOMINATE is designed for cross-era comparison; the SCDB conservative coding is consistent across the period.