Who Draws the Maps? Legislative and Congressional Redistricting

Every ten years, states redraw their congressional and state district lines. Each state determines for itself, usually detailed in the state constitution, who will draw district lines for state legislators and Congress members.

June 1, 2018

Every ten years, states redraw their congressional and state legislative district lines after the census. Each state, usually through its constitution, determines who will draw these lines.

The way districts are drawn can have a big impact. It can influence who wins elections, how political power is distributed, which communities are represented, and what laws are passed. This creates a powerful incentive to manipulate district lines for political gain. Over the last two decades, such manipulations have grown increasingly common and sophisticated.

However, recent years have seen a significant growth in efforts to protect the redistricting process from abuse. While the vast majority of jurisdictions continue to use their state legislatures for drawing districts, there is a growing movement toward alternative approaches to mapdrawing. Citizen-driven ballot initiatives sparked redistricting reform in Arizona in 2000 and in California in 2008 and 2010. Since then, New York in 2014 and Ohio in 2015 and 2018 also have adopted various types of reforms.

2018 could see a record number of citizen-led reform measures on the ballot in November.

Many state legislatures also are considering reforms to the way redistricting is done. Visit our Redistricting Reform Tracker for information on redistricting bills currently pending before legislatures.

The following maps show who is currently responsible for redistricting in the United States.

State Legislature

In most states, the state legislature passes redistricting plans as regular legislation. In most states, the plan must be approved with a majority vote in each chamber and is subject to veto by the governor, but some states have different requirements. Legislative plans in Arkansas, Connecticut, Florida, Maryland, Mississippi, Missouri, and Ohio are not subject to gubernatorial veto. Neither legislative nor congressional plans are subject to a gubernatorial veto in Connecticut and North Carolina. State legislatures currently are responsible for drawing legislative districts in 32 states and congressional districts in 34.

Advisory Commission

In some states, advisory commissions, which may consist of legislators or non-legislators or a mix, recommend redistricting plans to the legislature. An advisory commission draws the maps and the legislature has the final say in approving district maps, usually by an up or down vote. Connecticut and Maine require a plan to be passed with a 2/3 majority of the legislatures. Most states establish advisory commissions through their state constitutions, but Iowa’s advisory commissions is set up by statute. Three states use an advisory commission to draw congressional plans, and five states have an advisory commission to draw state legislative districts.

Independent Commission

Independent commission are made up of members who are neither public officials nor current lawmakers and are selected with the help of a screening process that is conducted by an independent entity. Commissioners are responsible for drawing and approving the final maps. Two states use an independent commission for both state legislative and congressional plans.

Political Appointee Commission

Another type of commission is a political appointee commission, which is a commission composed of individuals who are directly appointed by elected officials, party leadership, or political party committees. In some states, the membership of a political appointee commission is evenly divided between parties, but, other states allow members of one party to hold more seats on the commission than the other. Four states use a political appointee commission for congressional plans, and nine states use this type of commission for state legislative plans. Ohio uses a hybrid between a political appointee commission and a politician commission to draw its legislative districts.

Politician Commission

Two states use a commission where all members are incumbent lawmakers or other elected officials to create state legislative plans. Politician commissions are usually appointed by the legislative or party leadership, the governor, or chief justice of the state supreme court. In Missouri, a plan must be approved by 70% of the commission in order to pass.

Backup Commission

A few states use a backup commission to draw a map when the legislature is deadlocked or when the governor vetoes the proposal. Three states use a backup commission for congressional plans and five for state legislative plans. In Ohio, if the legislature fails to pass a map with bipartisan support, a seven-member backup commission would draw the congressional map.

Single District States

Seven states currently have only one congressional district.