Party switching is rare but consequential. When a sitting legislator changes labels — leaving one party for the other, or jumping to independent — the chamber's partisan math changes without any voter casting a ballot. In closely divided legislatures, a single switch can tip control or break a supermajority.
This page collects every recorded party switch by a state legislator or statewide officeholder we track. Use the historical chart to see which years saw waves of switching (the most famous: Southern Democrats reclassifying as Republicans through the 1990s and 2000s; more recently, a smaller stream of moderates leaving both major parties for independent status). Then browse the full list below — filterable by state, chamber, and direction of switch.
Party Switches by Year
Number of state legislators and statewide officeholders who changed party affiliation each year, colored by direction.
Browse All Switches
All Party Switches
| Year | Date | State | District | Name | Switch |
|---|
Methodology
A "party switch" is recorded when an officeholder changes their stated party affiliation between elections. Switches that happen at the start of a new term (an officeholder who reads as one party while running and another after being sworn in) and switches that happen mid-term (the more dramatic, news-driving kind) are both included; the "date" column shows when the change took effect according to our source.
Why some apparent switches don't appear here. Vermont Progressives who caucus with Democrats are not double-counted as switches — we treat the Progressive Party as a permanent affiliation, not a way station. Likewise, Nebraska's officially-nonpartisan unicameral has members with known caucusing patterns; their visible party label and their caucus label are stored separately, so a Nebraska legislator does not "switch" when our display flips between the two.
Coverage window. 2010 forward, drawn from our internal party_switches table. Pre-2010 switches are not systematically tracked.