Colorado is a rapidly-growing state that could gain one congressional seat following the 2020 Census. In 2018, we helped Colorado Democrats win the governor’s race, flip the Colorado state senate, and flip five seats in the Colorado House. We also supported the passage of Amendments Y & Z, which will bring fair congressional and state legislative maps to the state.


Redistricting in Colorado

The following timeline is a high-level overview outlining major redistricting events and activity in the state of Colorado over the last 10 years.


Census data delivered to Colorado.

A divided legislature failed to send a congressional map to Democratic Governor John Hickenlooper.

The legislature’s failure to draw a new congressional map spurred a flurry of litigation in Colorado state court. The district court adopted a new map proposed by one of the plaintiff groups during the litigation, and the Colorado Supreme Court affirmed that decision.

The map initially submitted by the Colorado Reapportionment Commission was rejected by the Colorado Supreme Court and returned for re-drafting. The Commission submitted revised plans, which were approved by the state Supreme Court.


President Barack Obama won the state with 51% of the vote and the congressional delegation was almost evenly split between Democrats and Republicans.


With the support of the NDRC, Democrat Jared Polis won the 2018 governor’s race by a 6-point margin with 51% of the vote.

On Election Day, Colorado voters passed Amendments Y & Z, a redistricting reform measure that will bring fair state legislative and congressional districts to the state, with a huge margin (70%). With the support of NDRC, Colorado Democrats also flipped the Colorado Senate and gained 5 seats in the Colorado House.

1 Redistricting Decision Makers

A 12-member independent congressional redistricting commission (four members from the state’s largest political party, four from the state’s second-largest political party, and four that are not affiliated with any political party) draws the congressional and state legislative maps. The final map requires the approval of eight of the 12 members, including at least two members that are not affiliated with any political party. The final map also requires approval by the Colorado Supreme Court. Under Amendments Y & Z, districts need to be competitive. “Competitive” is defined in the measure as having a reasonable potential to change parties at least once every 10 years. The maps approved by the commission and by the Colorado Supreme Court are final, meaning they are not subject to legislative approval, the governor’s veto or to veto referendum petitions.

2 Know Your State Legislature

Projected state legislature make-up starting in 2019.

Colorado Lower Chamber




Colorado Upper Chamber




1 Held by a third or unaffiliated party

Court Cases Impacting Colorado

Because the legislature could not agree on a map, the Colorado congressional map was decided in court.

Hall v. Moreno

Read the Colorado Supreme Court's decision in Hall v. Moreno.

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