The Daily Kos Elections Morning Digest is compiled by David Nir, Jeff Singer, Stephen Wolf, and Carolyn Fiddler, with additional contributions from David Jarman, Steve Singiser, Daniel Donner, James Lambert, David Beard, and Arjun Jaikumar.
Leading Off
● PA-06: On Sunday, Republican Rep. Ryan Costello announced he was dropping his bid for re-election, a move that utterly shafts his own party because it comes after last week’s candidate filing deadline. Costello’s suburban Philadelphia seat got quite a bit bluer due to court-ordered redistricting, and the new version of the 6th District went from 51-48 Obama to 53-43 Clinton. It would have been tough enough for the GOP to hold it with Costello, but his decision to bail so late in the game will force his party to find a last-second replacement for a very challenging race against Democrat Chrissy Houlahan.
Campaign Action
The biggest question left is whether Costello’s name will remain on the May primary ballot or whether he’ll remove it. The congressman told The Delaware County Daily Times that he hadn’t made this decision yet and would discuss it with party leaders. Team Red undoubtedly would prefer that he stays in the primary, if only in name.
The only other GOP candidate is tax attorney Greg McCauley, an unknown contender with no money in the bank, no public profile, and no apparent network of support: In other words, he’s exactly the type of person they don’t want as their nominee for an already-tough race. If Costello’s name stays on the ballot, he should have little trouble beating McCauley and claiming the nomination: Costello could then drop out and allow local Republican leaders to pick a new nominee.
But if Costello were to instead remove his name from the primary ballot, Team Red’s situation would go from bad to worst. Republicans would either have to try beating McCauley with a write-in campaign or knock McCauley off the ballot by challenging his petitions and then waging a write-in bid. If that fails, they’ll just resign themselves to his candidacy.
Normally, we’d assume that Costello would be a team player and technically remain in the race until he’d won the nomination, but he’s already chosen to make life miserable for his party. Had he just decided to retire a little while before the March 20 filing deadline, Republicans could have recruited another candidate who could have hit the ground running, and whose name would actually be on the primary ballot.
But while it’s surprising and catastrophic for the GOP that Costello has let all this happen to them, it’s not shocking that he ultimately decided to call it quits. The Pennsylvania Supreme Court recently put in place a new congressional map to ensure fairer elections, and Costello was not happy that he’d need to run in a seat Clinton had carried by 10 points instead of one she’d taken by just half a percentage point.
In fact, Costello was so miserable about this turn of events that he joined in with his fellow Republicans to demand the impeachment of the Supreme Court justices who ordered the new map and even called it racist (!). But while Costello wasn’t remotely quiet about his views about what should happen to the justices he hated, he wouldn’t deny rumors that he was thinking about retiring.
No matter what happens next, it won’t be easy for the GOP to find someone decent who wants to go through all the trouble of trying to hold this seat. Houlahan, a businesswoman and Air Force veteran, was already one of Team Blue’s top recruits before this seat was redrawn. She’s been running for over a year and has stockpiled nearly $1 million while earning endorsements from major power players like EMILY’s List, VoteVets, the DCCC, and Joe Biden.
And while political scientist Brian Amos writes that Republican Sen. Pat Toomey narrowly carried this district during his tight 2016 re-election campaign, this is exactly the type of suburban district where Trump is likely to be toxic for Team Red. And even though Republicans have traditionally done well down the ballot in this area, Trump may have already changed that. Last year, Chester County Democrats unseated the GOP incumbents in the races for treasurer, controller, coroner, and clerk of courts. According to party officials, the last time Democrats won these offices was in 1799 … Thomas Jefferson's Democratic-Republicans, that is.
Chester County makes up 71 percent of this district’s population (the balance is in Berks County around Reading), so if local voters are taking out their anger against Trump on Republican candidates for coroner, Republican candidates for Congress aren’t going to have a fun time.
P.S. Whatever happens with his seat, Costello’s decision now brings the GOP to a record-shattering 37 retirements for the cycle.
senate
● MS-Sen-B: Businessman Andy Taggart has confirmed that he remains interested in potentially running in the special election for Thad Cochran's Senate seat, even after Gov. Phil Bryant announced he'd appoint state Agriculture Commissioner Cindy Hyde-Smith to the post. Taggart had previously suggested he might run before Hyde-Smith got the nod and specifically cited the need for Republicans to "fend off" far-right state Sen. Chris McDaniel.
But Taggart may not exactly be the best guy for the job: Though he's a former executive director of the state GOP, he's also criticized Trump and called for the state to remove the Confederate battle emblem from the state flag. He was also the 2016 state campaign chair for John Kasich, who fared very poorly in Mississippi, finishing in third place with less than 9 percent of the vote.
● MT-Sen: Restoration PAC, a group primarily funded by major conservative donor Richard Uihlein, has begun what they say is a $500,000 TV buy in support of Auditor Matt Rosendale in the June GOP primary. Their first spot begins with the narrator framing the election as a choice between Democratic Sen. Jon Tester, whom the narrator characterizes as "someone who fakes Montana values around election time," and Rosendale "who lives them every day." He also argues that unlike Tester, Rosendale supports the GOP tax bill and opposes the Obama administration's nuclear deal with Iran. If this ad feels familiar, it's because Restoration PAC ran a very similar commercial in West Virginia earlier this month.
● ND-Sen: Days after the Koch brothers’ Americans for Prosperity group began a $450,000 ad campaign against Democratic Sen. Heidi Heitkamp for a vote to give special interests "billions in tax payer handouts," the Senate Majority PAC has launched a $400,000 buy defending her. The narrator begins by saying, "When out-of-state billionaires start running false negative ads against Heidi Heitkamp, she must be doing something right." He continues by saying Heitkamp's vote was for a bill that helped North Dakota farmers and small businesses, and GOP foe Kevin Cramer and Sen. John Hoeven voted the same way.
Gubernatorial
● AL-Gov: State Sen. Bill Hightower is one of a few Republicans challenging Gov. Kay Ivey in the June GOP primary, and he's the first Ivey rival to join her on TV. Hightower tells the audience that he's a businessman who is "tired of career politicians," so he wrote a term-limits bill restricting them to 12 years in office. (What he doesn't mention is that bill went down in defeat on Wednesday.) Hightower also calls a "simple, fair tax" and "cut[ting] wasteful spending by banning earmarks." If you enjoy listening to a guy sit in his living room and talk about taxes, this ad was practically made for you.
P.S. Does Hightower remind anyone else of Dr. Leon Spaceman from "30 Rock," or is it just us?
● MA-Gov: MassINC takes another look at GOP Gov. Charlie Baker's re-election prospects on behalf of WBUR, and they still find him far ahead of his three prospective Democratic foes. In a hypothetical general election matchup with Newton Mayor Setti Warren, Baker leads 58-24, which is exactly the same margin they found in November. Baker defeats former state budget chief Jay Gonzalez and environmentalist Bob Massie 60-21 and 59-22, respectively, and those numbers have also barely changed since November. And while Trump is broadly despised with a 27-66 unfavorable rating, Baker posts a very positive 66-14 score.
● MI-Gov, MI-Sen: The GOP firm Strategic National, which works for Lt. Gov. Brian Calley, is out with polls of the August Republican primaries. They give Attorney General Bill Schuette a 27-18 lead over Calley, while state Sen. Patrick Colbeck takes 7. Back in December, they gave Schuette a 30-19 edge; the only other poll we've seen in months was a February Schuette internal that found him beating Calley 42-15. In the Senate race to take on Democratic Sen. Debbie Stabenow, venture capitalist Sandy Pensler leads businessman and veteran John James 21-17.
Schuette, whom both campaigns agree is the frontrunner, also secured an endorsement on Thursday from the Michigan Chamber of Commerce. The Detroit News' Jonathan Oosting calls the state chamber a powerful and coveted endorsement in GOP primaries, but notes that their record isn't perfect. In 2010, they sided with then-Attorney General Mike Cox in the primary; two months later, Rick Snyder decisively beat then-Rep. Pete Hoekstra 36-27, while Cox took third with 23.
Snyder is again on the opposite side of the state chamber. Snyder stars in an ad from his Relentless Positive Action PAC for Calley, which begins with a brief clip of Snyder's 2010 "one tough nerd" commercials before the governor appears and says the state has come a long way since then. Snyder details his conservative record and says Calley "has been invaluable to our comeback" and says his one flaw is "he's way too cool to be a nerd." There is no word on the size of the buy; the Detroit News says the commercials will air on cable and broadcast TV in various markets.
Schuette is also taking to the airwaves with two ads, though the News says these don't seem to be running on broadcast television. One spot promotes how Trump is backing Schuette, while the other argues that Calley is a liberal who "deserted Donald Trump." Back in 2016 after the "Access Hollywood" tape seemed to kill Trump's campaign, Calley unendorsed Trump while Schuette stayed with him; expect to see a lot more ads on this topic before August.
● NV-Gov: In a new analysis of Democrat Chris Giunchigliani's campaign spending over the years, the Reno Gazette-Journal's James DeHaven reports that she paid her late husband's consulting firm more than $1 million between 1996 and 2014, roughly half of which was for her successful 2006 campaign for Clark County commissioner. Giunchigliani insists that her husband, Gary Gray, charged her the same rates as his other clients, but the amount of money he made on that one campaign, some $473,000, was more than the $462,000 paid to him over the following seven years by every other candidate he ever worked for, 18 in total.
In theory, there's nothing wrong with paying family members to work on your campaign, but Nevada ethics laws bar paying more than fair market value for such services, or paying for a "personal use." The reason why this might become an ongoing story is because, says DeHaven, Giunchigliani "did not answer questions from the Reno Gazette Journal about whether she had ever spent campaign funds for personal use." That's an astonishing stance to take—why not at least issue a denial—since spending campaign contributions for personal use is a serious offense. Former Illinois Rep. Jesse Jackson Jr., for instance, was sentenced to 30 months in prison for spending campaign money on himself.
Giunchigliani is currently running in Nevada's open governor's race, and she faces fellow Commissioner Steve Sisolak in the Democratic primary. By clouding the matter by refusing to address it in the first place, Giunchigliani is now going to have to offer a more detailed response if she doesn't want this to linger over her latest campaign.
● PA-Gov: While the state GOP is backing state Sen. Scott Wagner in the May primary, businessman Paul Mango is arguing he also has some prominent party supporters. Mango recently rolled out endorsements from 20 county commissioners in 16 counties. But weirdly, he included his running mate, Washington County Commissioner Diana Irey Vaughan, on the list, even though she was presumably supporting him before this.
House
● AZ-08: In an unexpected development on Friday afternoon, the Republican National Committee reported spending $281,000 on door-to-door canvassing for the special election in Arizona's 8th Congressional District in support of former state Sen. Debbie Lesko. Given that this district is even redder than Pennsylvania's 18th (Trump won it 58-37) and has a lower proportion of college graduates, it hadn't looked like a potential flip, even in the current political environment, but the RNC's expenditure suggests that perhaps it could be.
However, we haven't seen any significant third-party spending since February's primary, so national Republicans could simply be making this investment out of an abundance of caution. But even if that's the case, if the GOP feels compelled to shore up districts like this, that means they're still in serious trouble on bluer turf. We'll be keeping a close eye on any further signs that Lesko faces a real fight from Democrat Hiral Tipirneni, an emergency room physician, in their April 24 bout.
● FL-27: Democrat Donna Shalala is running her first TV ad, a positive spot that says she "helped create CHIP, delivering health care to millions of children" (while flashing a photo of her alongside a very young-looking Bill and Hillary Clinton) and "transformed the University of Miami into an academic powerhouse, delivering $6 billion annually to Miami-Dade's economy." The spot concludes by saying she's "ready to deliver on day one."
● MI-09: Former Gov. Jennifer Granholm has endorsed attorney Andy Levin in the Democratic primary to succeed retiring Rep. Sandy Levin, who is the candidate's father. The younger Levin served in Granholm's administration as a deputy and later acting director of the state Department of Energy, Labor and Economic Growth.
● MN-01: The League of Conservation Voters, which has a history of serious campaign spending, has endorsed attorney Joe Sullivan in the Democratic primary for Minnesota's open 1st Congressional District. There's no word, however, as to whether LCV plans to devote actual resources on Sullivan's behalf. Overall, this race still has yet to take shape, though former Defense Department official Dan Feehan has led in the money chase so far.
● NH-01: EMILY's List has endorsed Maura Sullivan, a former Department of Veterans Affairs official, in the September Democratic primary for this open swing seat.
● NJ-08: Hudson County Freeholder Tilo Rivas reportedly is considering challenging Rep. Albio Sires in the June primary for this safely blue seat, but the incumbent doesn't seem to be backing away from what could be an uphill battle. Sen. Bob Menendez, who represented much of this area in the House until he was appointed to the upper chamber in 2006, will hold a fundraiser for Sires on Monday.
● NJ-11: Montclair Township Councilmember Bill Hurlock didn't quite rule out a bid for the GOP nomination in January, and he now says he's considering getting in. However, he may have a tough time if he does run: GOP leaders in Hurlock's Essex County are supporting investment banker Antony Ghee, while Assemblyman Jay Webber has a base in populous Morris County.
● NV-03: The GOP firm Strategic National took a look at the GOP primary earlier this month, days before businessman and 2016 nominee Danny Tarkanian decided to run here. They gave Tarkanian a 37-10 lead over former TV reporter Michelle Mortenson; former Assemblywoman Victoria Seaman, who has since dropped out of the race, was tied with state Sen. Scott Hammond at nine each, while former Clark County party chairman Dave McKeon took one. Strategic National did not identify a client.
● NY-11: In perhaps the most Mike Grimm thing we could imagine, the once and perhaps future GOP congressman parked in a handicapped spot.
● NY-25: Rochester Deputy Mayor Cedric Alexander, who was previously the city's police chief, says he's considering the race to replace the late Louise Slaughter in New York's 25th Congressional District and expects to announce a decision in the coming week. While Alexander's party affiliation is not mentioned, he's a member of the administration of Mayor Lovely Warren, who is a Democrat (and who has herself not ruled out a bid).
● OH-12: Rep. Tim Ryan has endorsed Franklin County Recorder Danny O'Connor in the special election for Ohio's vacant 12th Congressional District. Ryan joins the local Democratic establishment in getting behind O'Connor, who faces several other Democrats in the May 8 primary. The special will be held on Aug. 7.
● PA-04: Gun-safety activist Shira Goodman is one of four Democrats seeking this 58-38 Clinton seat in Montgomery County, but she doesn't sound committed to staying in. The Philadelphia Inquirer's Maria Panaritis asked Goodman if she planned to keep running, she responded, "I'm not ready to make a decision right now because a man who used to be in Congress [Joel Hoeffel] decided to get in at the last minute," adding, "If somebody's a spoiler, it's up to the voters to see it." That's very much not a commitment to remaining in the contest.
What brought this question on is a fear among some party activists that Hoeffel's surprise campaign will keep a woman from winning this seat. Pennsylvania hasn't elected a single woman to its 18-member House delegation since Allyson Schwartz won her final term in 2012, and for a while, it looked like this district would break that streak. Goodman and state Reps. Madeleine Dean and Mary Jo Daley had the race to themselves until a few weeks ago, when Hoeffel jumped in. Hoeffel recently released an early March poll conducted before he got in that showed him leading Dean 25-17, while Daley and Goodman took 9 and 5 percent, respectively.
But while Goodman sounds iffy about staying in, Daley was more direct, saying she wasn't "gonna fall on a sword." And Dean seems to have the most establishment support and resources, so she's not likely to go anywhere.
Grab Bag
● Deaths: Former Georgia Gov. and Sen. Zell Miller, a Democrat, died Friday at the age of 86, leaving behind a very complicated political legacy. One the one hand, Miller was identified as a progressive governor (especially for a Southern state) during the 1990s, and he’s remembered for creating the HOPE scholarship, which has allowed almost 2 million Georgians to attend college. On the other, he rose to national prominence in 2004 for campaigning for George W. Bush despite still identifying as a Democrat, and he continued to back conservative candidates for the rest of his life.
Miller, who grew up in the small community of Young Harris in rural northeast Georgia, became its mayor in 1959 at the age of 27 after a stint in the Marines. Miller, who was also working as a professor at Young Harris College, won a seat in the state Senate the next year as a Democrat. He notably did oppose a school segregation bill from the floor of the chamber during his first year in office, but he was far from a supporter of Civil Rights at that early point in his career.
Miller challenged six-term Rep. Phillip Landrum in the primary in 1964 for a seat in the northeast corner of the state. While Landrum was a staunch segregationist, Miller argued during that campaign that President Lyndon Johnson was "a Southerner who sold his birthright for a mess of dark pottage," comments he would later disavow. Miller lost 52-43, and he lost his 1966 rematch to Landrum 54-40.
Miller soon landed on his feet and rose to become chief of staff to Gov. Lester Maddox. While the governor was a notorious segregationist, observers credited Miller for being a moderating influence on him. Jimmy Carter, Maddox's successor and longtime rival, went on to appoint Miller to the state Pardons and Paroles board. Miller ran for lieutenant governor in 1974 and defeated, among many others, his future Senate colleague Max Cleland in the primary. Miller would go on to spend 16 years in the office, the longest anyone ever held that post.
However, Miller tried to leave it in 1980 when he challenged four-term Sen. Herman Talmadge in the primary. Talmadge, a longtime Georgia institution and the chair of the powerful Agriculture Committee, was facing a number of ethics problems (he had been denounced by the Senate for "gross neglect of his duty"). Talmadge had also gone through a messy divorce, and he had a well-known drinking problem. Polls initially showed Talmadge trailing Miller by as much as 17 points, and the incumbent only took 42 percent of the vote to Miller's 24 in the first round. Miller, who had the support of prominent black politicians as well as organized labor, argued the incumbent was dishonest and an embarrassment.
However, Talmadge rebutted Miller's attacks on his character by portraying him as a big-spending liberal. And while the senator, who had once been a vocal segregationist, had apologized for his previous stances, he repeatedly reminded rural voters that Miller was supported by two well-known black politicians, Atlanta Mayor Maynard Jackson and state Sen. Julian Bond. Talmadge beat Miller 59-41, but the damage was done, and he lost in November to Republican Mack Mattingly in a shocker. During that campaign, Miller acquired the nickname "Zig Zag Zell" for allegedly being so unpredictable. Miller hated it at the time, though he'd later admit there was some truth to it.
Miller decisively won two more terms as lieutenant governor afterward, and he sought the governorship in 1990. Miller faced a crowded primary against Atlanta Mayor Andrew Young, state senator and future Gov. Roy Barnes, and even Lester Maddox, his old boss. Miller campaigned on setting up a state lottery to fund education and other programs, which was a very risky proposal in a state with a large conservative Christian voter base. The lieutenant governor took first place in the primary with 41 percent, while Young outpaced Barnes 29-21 for the second runoff spot.
While Young tried hard to drive up black turnout and win over enough white voters to become the state's first African American governor, Miller was always seen as the favorite. Miller beat Young 62-38 and went on to defeat state House Minority Leader Johnny Isakson, a Republican who would succeed him in the Senate 14 years later, 53-45.
As governor, Miller successfully pushed both the legislature and voters to approve the HOPE scholarship program, which paid college tuition to students who maintained a B average. The program was funded by the state lottery Miller established. Miller also convinced the legislature to end the food sales tax, and he appointed an unprecedented number of women and people of color to executive and judicial posts.
Miller, who was a close friend of Arkansas Gov. Bill Clinton, was also a prominent supporter of his 1992 presidential campaign. Miller was one of the keynote speakers at that year's Democratic National Convention where he declared, "We can't all be born rich and handsome and lucky, and that's why we have a Democratic Party."
However, Miller soon ran into political opposition at home. As Atlanta prepared to host the 1996 Summer Olympics, business leaders pressured him to remove Confederate imagery from the state flag. Miller took up the cause, saying in his State of the State address that the Confederate symbolism had been added in 1956 "to identify Georgia with the dark side of the Confederacy — the desire to deprive some Americans of the equal rights that are the birthright of all." But the legislature didn't go along with him, and he eventually gave up.
Miller faced a difficult campaign in 1994 against businessman Guy Millner, a Republican who ran ad after ad featuring clips of Miller praising Clinton at the DNC. Miller ended up winning re-election in the GOP wave year just 51-49, and the HOPE scholarship's popularity was probably what saved him.
Miller left office in 1999 with an 85 percent approval rating, and he soon returned to teaching. But in the summer of 2000, Republican Sen. Paul Coverdell died, and it was up to Democratic Gov. Roy Barnes to appoint his successor. Miller had turned down Clinton's attempts to recruit him to challenge Coverdell in 1998, and he was reluctant to accept a Senate appointment. But Barnes was convinced only the popular Miller could win the seat for the Democrats, and Miller eventually gave in. Miller beat Republican Mack Mattingly, the man who had defeated Herman Talmadge after the bitter 1980 primary, 58-38 to win the final four years of Coverdell's term.
Miller had accepted the appointment saying he wouldn't "play the partisan game" in Washington, and he was anything but a loyal Democrat. Miller was an early and enthusiastic supporter of George W. Bush's tax cut bill. Miller later said that the September 11 attacks also changed him. He became more and more socially conservative in DC: While he had supported abortion rights as governor and invited the Gay Games to Atlanta, he had since become an angry abortion foe and supported a constitutional amendment to outlaw same-sex marriage.
Miller did back his colleague Max Cleland's 2002 re-election campaign by appearing in ads for him. Republican Rep. Saxby Chambliss tried to use Miller as a wedge against Cleland by arguing that his opponent had supported the Democratic leadership far more than Miller had, and highlighting how Miller was considerably more conservative. Miller defended Cleland by reassuring TV viewers that the two senators voted together more than 80 percent of the time; Miller also appeared in ads for Barnes, who was in a tough re-election campaign for governor. But both Democrats lost, and Miller wouldn't support another Democrat in a major race for a long time to come.
Miller decided not to seek another term in 2004, and while he never switched parties, he became a full-throated supporter of Bush's re-election campaign. Miller delivered the keynote address at the 2004 Republican National Convention where, among other things, he proclaimed that Democratic opponent John Kerry was "more wrong, more weak and more wobbly than any other national figure" on national security; just three years before, Miller had introduced Kerry at a Democratic dinner as an “authentic hero.”
Right after his RNC speech, Miller appeared on MSNBC afterwards and got into a nasty fight with host Chris Matthews. Miller concluded the interview by telling Matthews, "I wish we lived in the day where you could challenge a person to a duel!" The duel never happened, and while Miller would later say in 2012 that he "embarrassed myself," he added that Matthews "is not one of my favorite people."
Miller remained an impassioned Democratic critic in retirement, and he promoted Republican candidates at home. Miller appeared in a 2006 ad for GOP Gov. Sonny Perdue even though Democratic candidate Mark Taylor had been a Miller ally during his governorship. And while Miller had opposed Chambliss during the 2002 campaign, he urged Georgians to re-elect him six years later because he "could well be the last man standing between a far, far left liberal agenda sailing through the Senate." Miller was no fan of Barack Obama either, and he supported Newt Gingrich's 2012 presidential bid.
But while Miller backed GOP Gov. Nathan Deal's 2014 re-election campaign, "Zig Zag Zell" still had one more surprise in him. That same year, Miller starred in an ad for Democratic Senate candidate Michelle Nunn extoled her as a bridge builder who can work across party lines. While it was possible he was doing it out of respect for her father, former Sen. Sam Nunn, Ed Kilgore at the Washington Monthly argued that Miller might have just admired Nunn's nonprofit work. Kilgore also observed that Miller was proud of his record of appointing women to important posts as governor, and might have seen Nunn as a continuation of that legacy.
● Demographics: The Census Bureau's annual Population Estimate, released on Thursday, shows that population growth remains the strongest in Sun Belt states (especially Texas, though maybe not to the extent we've seen in the last few previous years). Among metropolitan statistical areas (MSA), the top two for numeric growth were Dallas and Houston, followed by Atlanta, Phoenix, and Washington, D.C.
By percentage gain, however, only one of the 10 biggest-gaining MSAs was in Texas (Austin); the biggest gainers were the retirement destinations of St. George, Utah, and Myrtle Beach, South Carolina, followed by some cities in the Mountain West that are popular destinations for people fleeing California: Greeley, Colorado; Bend, Oregon; and Coeur d'Alene, Idaho. Somewhat surprisingly, the MSA for the dystopian retirement community of The Villages, Florida, seems to have leveled off a bit after leading this category for a number of years; it ranked only 10th for percentage growth in 2017.
If you switch to counties, the biggest numeric gainers shouldn't surprise anyone: Maricopa County, Arizona (Phoenix); Clark County, Nevada (Las Vegas); Riverside County, California; Harris County, Texas (Houston); and Tarrant County, Texas (Fort Worth). Neither should the biggest numeric decreases, which were mainly in Rust Belt cities: Cook County, Illinois (Chicago); Baltimore city, Maryland; Cuyahoga County, Ohio (Cleveland); St. Louis city, Missouri; and Allegheny County, Pennsylvania (Pittsburgh).
But the biggest gainer by percentage is an unusual one: the independent city of Falls Church, Virginia, which is boxed in by other suburbs and must have gained through significantly increased density. Following that are three Texas counties in the exurban corridor between San Antonio and Austin (Comal, Hays, and Kendall Counties), and a county in rural Utah, Wasatch County.
Jeb Kolko, writing for CityLab, takes an interesting closer look at the political leanings of the gainers and losers, finding that blue counties are losing a lot of population via domestic migration to red counties (which may have a lot to do with exorbitant housing expenses in a number of major metros), but that blue counties are replenishing their population by outpacing the red counties in both international migration and in natural increase (i.e. births minus deaths). He also notes that a lot of the blue county-to-red county domestic moves are to counties that are only narrowly red and moved in the Democratic direction last year, citing Dallas's suburbs as a key example.