US Redistricting Methods Differ Sharply From Other Democracies

How legislative districts are drawn varies widely among democracies, with the United States following a process that stands out for its decentralization and legislative involvement.

In the US, most states redraw congressional districts every ten years after the national census, and in 25 states, the responsibility for setting district boundaries falls primarily to the state legislature. This approach is unusual among democracies, as only the Federated States of Micronesia uses a similar system where subnational legislatures play the main role in drawing single-member districts.

As of 2025, nine US states have adopted independent redistricting commissions to oversee the drawing of both congressional and state legislative districts. These commissions are structured to exclude legislators and public officials from membership, aiming to separate the process from direct political influence.

Other democracies have established independent bodies at the national or provincial level to manage redistricting. In the United Kingdom, boundary commissions operate independently of government and parliament, reviewing and redrawing parliamentary constituencies every eight years. Canada also relies on independent commissions in each province to determine House of Commons ridings, while New Zealand’s Representation Commission is responsible for setting boundaries for its House of Representatives.

What the numbers show

• 25 US states assign primary redistricting responsibility to their legislatures
• Nine US states use independent commissions for redistricting as of 2025
• UK boundary commissions redraw constituencies every eight years

Mexico’s National Electoral Institute, which serves as the country’s top election authority, is tasked with drawing single-member districts for the Chamber of Deputies. These approaches contrast with the US, where the process is more fragmented and often involves direct legislative control.

In countries that use multimember districts, such as several parliamentary democracies, adjustments are typically made to seat allocations rather than redrawing district lines. This method reduces the political significance of how boundaries are set, as compared to systems that rely on single-member districts.

The US redistricting process is characterized by a high degree of decentralization and frequent political involvement, which can result in irregularly shaped districts. Courts in the US regularly intervene in redistricting disputes, particularly those involving allegations of racial or partisan gerrymandering.

Independent commissions in the US are intended to limit partisanship by preventing lawmakers and public officials from participating directly in the redistricting process. Research indicates that districts drawn by independent commissions or courts are associated with increased voter turnout and more competitive elections compared to those drawn by legislatures.

In the UK, boundary commissions conduct public consultations over a two-year period and operate without oversight from parliament or government ministers. This process is designed to ensure that redistricting decisions are made independently and with input from the public.

* This article is based on publicly available information at the time of writing.