Only 20 Times Since 1992 Have Both State Legislative Chambers Flipped Partisan Control

Simultaneous changes in partisan control of state legislatures are rare, with just 20 instances in the past 34 years.

Published on Feb. 27, 2026

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According to an analysis by Ballotpedia, since 1992 there have been 160 changes in state legislative chamber partisan control across the country. However, only 20 times (14%) have both of a state's legislative chambers changed partisan control in the same year, with 11 flips from Democratic to Republican and 8 from Republican to Democratic. The most common scenario is for a single chamber to change control (86% of cases), with 78 lower chambers and 82 upper chambers seeing partisan shifts since 1992.

Why it matters

Simultaneous changes in partisan control of state legislatures are significant political events, as they can shift the balance of power and influence issues like redistricting, legislation, and policy priorities. While split control of state chambers is common, full partisan flips of both chambers in the same year are relatively rare.

The details

The analysis found that the most instances of both chambers flipping occurred in 2010, when six states saw their legislative chambers change from Democratic to Republican control. Three states - Maine, Minnesota, and Nevada - had both chambers flip twice between 1992 and 2026, while New Hampshire saw all four partisan changes in that time period. Overall, 120 individual chamber changes occurred, with Washington and Wisconsin seeing the most at 8 each.

  • The analysis covers changes in state legislative chamber partisan control since 1992.
  • The most recent year with 10 or more changes in chamber control was 2014.

The players

Ballotpedia

A nonprofit and nonpartisan digital encyclopedia of American politics and elections.

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What they’re saying

“The Republican midterm wave swept through state capitals across the nation Tuesday, with historic gains in state legislative races that will give the GOP a major advantage in influencing congressional races over the next 10 years through redistricting.”

— Joseph Weber (The Washington Times)

The takeaway

While single-chamber partisan flips are relatively common, simultaneous changes in control of both state legislative chambers are quite rare, occurring just 20 times since 1992. These events can have significant political implications, making them important to track and understand.