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Colorado’s 1st Congressional District in Denver and the 4th District, which sweeps across the Eastern Plains and into Douglas County, stand to change the most this year when an independent commission redraws districts based on 2020 Census numbers, a Colorado Sun analysis shows.

Each of Colorado’s seven U.S. House districts will lose population and geographic area if, as expected, the state gains an eighth seat after 2020 census results come in. Between 2010 and 2019, the state’s population grew 14.5%, to nearly 5.8 million people from 5 million. 

That will pose the most significant changes to the districts since 2001, when Colorado received a seventh House seat. And while the release of 2020 census numbers is delaying the process, political experts and hobbyists are spending time speculating about new congressional boundaries.

So the Colorado Sun took a look at current districts using 2019 population estimates.

MORE: Colorado’s new redistricting process needs you — yes, you — to help decide the political districts

Where Colorado’s population has increased most

The 4th District, represented by Rep. Ken Buck and encompassing Weld County and the Eastern Plains, stands to contract the most, according to the Sun analysis. It’s followed by the 1st District represented by Democrat Diana DeGette and based in Denver.

The massive 3rd District, represented by Republican Rep. Lauren Boebert, would shrink the least under those projections. But it’s possible CD3 could change significantly, as Democratic-leaning Pueblo County lobbies to be removed from the district, which stretches across the San Luis Valley to the western border then up through Grand Junction and Steamboat Springs. 

Such decisions will be up to a 12-member independent commission, which is still in the process of being formed. It will initially consider maps drawn by nonpartisan legislative staff. The panel, created when voters passed Amendments Y and Z in 2018, is slated to hold hearings in each current congressional district.

“The most growth has been along the Front Range, from Larimer and Weld down to Pueblo,” State Demographer Elizabeth Garner said. “About a third of our counties have declined in population.”

Most of that decline came in the rural southeastern and northwestern parts of the state, Garner said.

Data from the Census to use in the process won’t be released until the end of September, a lengthy delay from the original plan to release the data in late March that is tossing uncertainty into the redistricting process The redistricting commission is supposed to have the maps done by the middle of September and the Colorado Supreme Court must approve final maps by Dec. 15.

But that delay isn’t stopping political operatives and analysts from speculating how lines might be redrawn. 

“The numbers tell a story,” said Alan Philp, a Republican consultant who worked on maps in 2001 and 2011. “It’s pure coincidence, but Denver and El Paso County are almost one congressional district each. The Western Slope is almost one district.”

Scott Martinez, a lawyer who helped draw Democratic congressional maps adopted by state courts in 2001 and 2011, said it’s too soon to speculate about how districts might be drawn. He said he’s waiting for the official Census numbers to come out.

“If they start with Pueblo, you get one map. If they start with Denver, you get another map,” Martinez said. “It’s really anyone’s guess what all eight districts will look like.”

Still, 2019 population estimates offer hints about how current districts will need to change. Each of eight districts would have nearly 720,000 voters based on those estimates.

Plenty of possibilities

Philp is correct that Denver and El Paso County could potentially be standalone congressional districts. Republican Rep. Doug Lamborn represents the El Paso-centric 5th District, which may lose Fremont, Teller and Chaffee counties, as well as parts of Park and Lake counties.

If Pueblo County were removed from the 3rd, other areas would need to be added. That could include counties removed from the 5th District, as well as eastern Eagle County and Summit and Grand counties, which are currently in the 2nd District.

Larimer, Weld and other northeastern Colorado counties could combine to form a new 4th District. Such changes to the 3rd and the 4th districts also would alter the 2nd District, centered in Boulder and Broomfield and represented by Democrat Joe Neguse of Lafayette. 

“The commission may go in a different direction, but some of those districts kind of draw themselves,” Philp said. “Once you get into the metro area, you’ve got a lot of ways to go.”

Ryan Brune is a statistics graduate student at Ohio State University who draws redistricting maps as a hobby and shares them on Twitter. He recently shared two Colorado maps with eight districts drawn using Dave’s Redistricting site, which allows people to create their own congressional boundaries.

One of the maps he calls the “least-change map. Every incumbent on this map lives in their current district.” It keeps Pueblo in the 3rd CD and centers the new 8th District in Jefferson County, which would potentially be a political toss-up.

Another would combine Douglas County and much of Jefferson County to make up a Republican-leaning 8th District.

David Wasserman, an analyst at Cook Political Report, hypothesized last week that the 8th might be centered in Weld and Larimer counties or in Denver’s southern suburbs, including Douglas County.  

Want to try your hand at drawing Colorado congressional maps? Check out Dave’s Redistricting, Districtr or DistrictBuilder. Some of the sites use 2010 data, while others offer the option of using 2018 population estimates.

Want to share your maps? Send a link or screenshot to, along with your name, city and a bit of description about your reasoning on redrawing the state’s congressional districts. We may share your maps in a story.

Commission considerations include keeping communities together

The top priorities for drawing new districts are equal population, contiguous boundaries, keeping cities and counties together when possible, compactness and competitiveness.

The Brennan Center for Justice at New York University describes Colorado’s new redistricting system under Amendments Y and Z as “particularly robust” with a strong independent commission drawing the maps. It’s one of six states that reformed their redistricting process after the 2011 reapportionment.

“Colorado’s new system is among the most independent, and one of the systems designed with the most safeguards in place,” said Yurij Rudensky, a redistricting counsel at the Brennan Center. 

Removing partisanship from the process was one of the factors used to urge voters to adopt the new commission in 2018. Previously, the legislature was responsible for drawing congressional districts. But deadlocks between Democrats and Republicans meant the courts actually selected the new maps.

Rudensky said care should be taken not to divide large populations of people with similar ethnicities during redistricting. In other states, districts have been drawn to dilute the influence of Black or Hispanic populations. 

Diversity will be a factor in Colorado, demographer Garner said.

“The biggest changes that we’re expecting between 2010 and 2020 is an increase in diversity. We should see more diversity in the voting-age population than we’ve seen historically,” she said.

Even counties on the Eastern Plains, where population remained stable or dropped, saw an increase in non-white people moving in for agricultural jobs, Garner said. That diversity also spread west along the Interstate 70 corridor to ski areas.

Still, map hobbyist Brune said, “it’s impossible to make a Hispanic district in Colorado.”

Rudensky said ethnic and racial diversity could figure into the 6th District, currently represented by Democrat Jason Crow. The 6th includes Aurora as well as other parts of Adams, Arapahoe and Douglas counties.

 “You look at places like Aurora and the way that city has grown and changed. Latino populations are growing, they will continue to grow over the coming decade,” Rudensky said.

Philp and Martinez share a common desire for the new process: Both hope to see competitive districts.

“I believe in competitive districts because they’re good for democracy,” Martinez said.

A map of Colorado’s seven congressional districts. (Handout)

Said Philp: “I just want the system to work. I just want a fair map.”

Meanwhile, Democratic and Republican politicians are anxiously awaiting the boundaries for the new 8th District, hoping to throw their hats in the ring. A number of big-name politicians are weighing a congressional bid should the new district be in the south Denver metro area, including Democratic state Sen. Jeff Bridges and Republicans George Brauchler, the former 18th District attorney, and state Reps. Patrick Neville and Colin Larson.

“Redistricting is going to be the biggest blockbuster political event in 2021,” Martinez said. “I hope the movie lives up to the hype.”

Special to The Colorado Sun Twitter: @fishnette