Salt Lake County is a census winner, but will end up a redistricting loser. Here’s why.

Salt Lake County expanded by a whopping 156,000 people over the past 10 years, and the capital city it encompasses has reached historic population levels, newly released census figures show.

Still, because of even more explosive growth elsewhere, residents of Utah’s most populous county are poised to lose some representation when officials redraw the boundaries of the state’s congressional and legislative districts this year.

This finding from a legislative analysis, based on census numbers released last week, offers an early look at the rebalancing act that redistricting officials will have to undertake as they adjust boundaries to account for Utah’s population shifts.

The review, presented to Utah lawmakers Monday, found that Salt Lake and Weber counties now account for less of the state’s population than they did in 2010 — so they’ll have to cede ground. On the other hand, Utah and Washington counties now represent a slightly higher share of total state residents.

“This makes a big difference in redistricting,” Jerry Howe, strategic initiatives manager in the Office of Legislative Research and General Counsel, told the Utah Legislative Redistricting Committee.

Salt Lake County will have to sacrifice 4% of a congressional seat, 30% of a state Senate seat, 77% of a state House seat and 15% of a state school board seat, according to the analysis. On the other hand, Utah County will gain 6% of a congressional seat, 43% of a state Senate seat, one whole state House seat and 22% of a state school board seat.

The once-per-decade task of designing the nation’s election districts is contentious in many states, often fraught with allegations that the ruling party is using partisan gerrymandering to protect incumbents and tilt the balance of power further in the party’s favor.

To combat these partisan influences, Utah voters in 2018 passed an initiative calling for an independent redistricting commission to help draw district maps. This year will mark the first time — after some legislative tinkering last year — that this new process unfolds. In November, the independent panel will offer recommendations to the Legislative Redistricting Committee, which can consider them but does not have to follow them.

“I truly believe that these next maps that come out, that these will be the best maps that we can do to represent the state of Utah,” Carson Jorgensen, Utah Republican Party chair, said Monday during a news conference hosted by the independent commission.

His counterpart in the state Democratic Party expressed hope that the Legislature will adopt the independent commission’s maps — even if lawmakers aren’t bound by the recommendations.

“I will be more than willing to admit that there are ways that I would love to see lines drawn,” said Jeff Merchant, Utah Democratic Party chair. “But as a Utahn, as an American and as someone who believes in democracy, I think that we have to be looking at ways to improve a system that is clearly broken.”

What do the new census numbers mean for Utah’s congressional districts?

Equally dividing Utah’s population of nearly 3.3 million people among its four congressional seats gives you the ideal district size of 817,904 people. The redistricting committee will use this number as a target and can’t stray far from it, with an allowable deviation of no more than 0.1% in either direction.

Only one of Utah’s congressional districts, the hotly contested 4th District, is currently oversized — exceeding the 817,904 threshold by 65,265 people, according to the census data released last week. Freshman Republican Rep. Burgess Owens currently holds the seat in the district, home to some of the nation’s most competitive congressional races.

The other three districts, where Republicans typically roll to easy victories, are below the target. The 1st District, represented by first-term Rep. Blake Moore, falls short by 17,807 people; District 2, represented by Rep. Chris Stewart, falls short by 16,268 people; and District 3, represented by Rep. John Curtis, falls short by 31,190 people.

To level out those discrepancies, the 4th will have to contract and give some of its residents to the other three districts.

How about for Utah’s legislative seats?

The ideal population for each of Utah’s 29 Senate districts will be 112,814 in this round of redistricting. But the legislative committee will have a bit more wiggle room in designing state-level districts and will simply have to keep each within 5% of the target size.

Twelve of the existing Senate districts have unacceptably small populations by this standard, while six have unacceptably large ones. The remaining 11 fall within that allowable 5% range, according to legislative analysts — although that doesn’t make them immune from boundary changes, because adjustments elsewhere could have a cascading effect across the map.

The redistricting groups will be aiming for a population of 43,622 in each of the state’s 75 House districts. Thirty-six of the existing districts have too few people, 20 have too many, and 19 are within the acceptable range.

A couple of the overpopulated districts encompass fast-growing parts of southwestern Utah, while others cover booming communities in Salt Lake and Utah counties. Two districts — one including Herriman and the other including Eagle Mountain and Saratoga Springs — currently hold almost double the target population.

How can Utahns get involved in this process?

Early next month, members of the Legislative Redistricting Committee will begin holding a series of town halls across the state. They won’t have any maps to present, but they will be listening to public feedback about how they should draw district lines.

The schedule is posted online at redistricting.utah.gov/town-halls.

You can also submit comments to the independent commission as it conducts its parallel map-drawing process.

Both committees will invite residents to submit their own suggestions about where district lines should fall. The Utah Independent Redistricting Commission debuted its online mapping tool Monday, while the legislative committee will be rolling out its version in early September.

“A lot of minds look at it and come up with as many varieties of solutions as you can find,” Howe said Monday, “because you never know who’s going to stumble on the one that just works for everybody.”