The U.S. economy has added some 19 million jobs in the past four years — all the jobs lost in the pandemic plus millions more. The comeback has been faster and more complete than any in recent decades, or maybe ever.

But it has also been uneven.

In some parts of the country, jobs came back quickly once vaccines were available, if not earlier. In many of those places, more people are working, and earning more money, than ever before.

In other places, the rebound has been much slower. As of 2023, more than two in five U.S. counties — 43 percent — still hadn’t regained all the jobs they lost in the early months of the pandemic, according to annual data from the Bureau of Labor Statistics. Some of those places were struggling long before 2020. Others had been thriving economically and were knocked off course by an airborne shock few saw coming.

The geography of that unequal recovery helps reveal how the pandemic — and the policies adopted in response to it — reshaped the U.S. economy, changing the kind of work Americans do and where they do it.

The patterns could have electoral implications: The battleground states that will help decide November’s presidential election include some of the biggest winners in the recovery — but also several of the losers.

The winners have some things in common. They are concentrated in the South and the Mountain West, particularly in suburban counties, which have done well in an era of remote and hybrid work.

They tend to be places where job losses were comparatively mild in the first place, often because their major employers were in industries that were less affected by — or that even benefited from — the disruptions of the pandemic. They are, on average, richer and better educated than counties that have been slower to rebound. They voted disproportionately for Donald J. Trump in the 2020 presidential election.

The losers, by contrast, tend to be concentrated both in big cities, which were hit particularly hard by the pandemic, and in rural areas, which were struggling long before the virus struck. They are relatively poor, on average, but with notable exceptions: San Francisco and several of its wealthy neighbors, for example, have yet to regain all the jobs they lost in the pandemic.

The pandemic also changed the types of jobs that Americans hold. Restaurants, hotels, movie theaters and other in-person businesses laid off millions of workers, while warehouses and trucking companies went on a hiring spree to meet the surge in demand.

Those shifts have reversed, but gradually and incompletely: The United States has more truck drivers and fewer waiters, as a share of the work force, than it did in 2019.

The economic changes that started in the early days of the pandemic have played out differently in different parts of the country — including the states most likely to decide the election. Nevada, which depends more heavily on tourism jobs than any other state, was hit especially hard in the pandemic, and while Las Vegas is booming again, not all the jobs have returned. That may help explain why both major presidential candidates have sought to woo casino workers there by promising to eliminate taxes on their tips.

Hospitality jobs have also been slower to return in the Northern swing states like Michigan and Pennsylvania than in Sun Belt states like Georgia and Arizona, where pandemic restrictions were lifted earlier.

Government policies have also helped shape the rebound in the job market. Big federal investments in infrastructure, green energy and high-tech manufacturing under President Biden helped fuel rapid hiring in manufacturing and heavy construction.

In Nevada, new factory jobs — and jobs building those factories — helped offset the slow rebound in tourism. Arizona has enjoyed one of the biggest construction booms of any state thanks partly to giant new chip manufacturing plants whose funding includes federal grants.

Partly because of these patterns, battleground states in the Sun Belt have thrived in recent years, at least in job growth. Maricopa County, Ariz., which includes Phoenix and is the site of the chip plants, is one of the fastest-growing big counties (those with at least one million residents) in terms of employment. Jackson County, Ga., is one of the fastest growing of any size — up more than 60 percent since 2019, partly because of a major new plant that manufactures batteries for electric vehicles.

That rapid growth has brought opportunities, but also challenges, particularly a critical shortage of affordable housing. It is no coincidence that the presidential campaigns of Mr. Trump and Vice President Kamala Harris have put housing at the center of their economic messages.

The Northern “Blue Wall” states face a different set of challenges. They struggled economically before the pandemic and have been laggards in the recovery.

Pennsylvania, for example, largely missed out on the construction and manufacturing booms. Allegheny County, which includes Pittsburgh, is the only big county in the country where total employment has fallen more than 5 percent since 2019. But the losses have been widespread: Of the state’s 67 counties, 51 lost jobs from 2019 to 2023.

How, exactly, these trends will play out on Election Day is unclear. Polls show that voters are worried about the economy across the country, not just in the places where the recovery has been weakest. That may be because, at least until recently, many Americans have been worried less about finding a job than about the rising cost of living.

That could be changing now, as rising unemployment and slowing job growth have begun to expose cracks in the labor market’s foundation. That is especially true in states like Pennsylvania, where hiring has lagged, but even fast-growing states have areas where the labor market is struggling.

While the election will probably be decided by voters in a handful of battleground states, nearly every place looks different than it did four years ago.

In Lee County, Fla., a wave of construction helped offset a big decline in hotel and restaurant jobs. Portsmouth, Va., bucked the national trend and added hospitality jobs due mostly to the opening of the state’s first permanent casino. McLean County, Ill., has gained thousands of manufacturing jobs in recent years, many of them at the electric vehicle maker Rivian.

See what has changed in your county:

The reincarnation of a shuttered Los Angeles retail mecca as a sprawling UCLA research center has received a major boost from billionaire philanthropist Dr. Gary Michelson and his wife, Alya, who will give $120 million to ramp up the project.

Michelson, a spine surgeon and inventor, said the money will help launch the California Institute for Immunology and Immunotherapy, which aims to create breakthrough discoveries that prevent and cure diseases including cancer, heart disease and Alzheimer’s.

The institute will be a tenant in UCLA Research Park, which is under construction in the former Westside Pavilion. The indoor mall two miles south of the university at Pico and Westwood boulevards was a 1980s icon popular with shoppers and filmmakers before falling out of favor. Most of its stores closed by 2019.

The shopping center was being converted to offices when the UC Regents bought it for $700 million in January to create the research park. Along with the California Institute for Immunology and Immunotherapy, it will house the UCLA Center for Quantum Science and Engineering, as well as other science and medicine programs.

By purchasing the former shopping center, UCLA saved years of toil to build such a facility on its campus, which is the smallest of the nine UC undergraduate campuses and has very little room for growth.

“That building would have gone on the last available piece of property on the UCLA campus,” Michelson said, “and it would have been extraordinarily expensive to build there. As a real estate matter, this was just an extraordinary opportunity.”

The immunology institute had been planned for years, while a full-scale research park was something “we’ve always dreamed of having … but we always recognized we could never find a piece of property that big close to campus. We had sort of given up on the idea many years ago — and it came alive,” said former UCLA Chancellor Gene Block, who was instrumental in the purchase of the former Westside Pavilion.

An earlier plan to build the institute on the campus called for tearing down a parking garage, digging a hole deep enough to replace the parking and erecting a new building on top, Block said.

The gift, through the Michelson Medical Research Foundation, designates $100 million to establish two research entities within the institute, each funded with $50 million; one will focus on rapid vaccine development and the other on harnessing the body’s microbiome to advance human health. The microbiome research will be conducted in collaboration with the new UCLA Goodman-Luskin Microbiome Center, placing it among the largest microbiome research enterprises in the world, the foundation said.

The foundation is also funding a $20-million endowment to provide research grants to young scientists using novel processes to advance immunotherapy research, human immunology and vaccine discovery.

The institute have labs of different sizes meant to serve biotech researchers who can start with small teams that can grow into larger labs if they find success.

“We’re going to create an entire ecosystem of biotech startups and they’re going to stay right here” and attract other players to the neighborhood, Michelson said. “We’re going to build out an entire ecosystem of biotech all through Westwood.”

He envisions 5,000 people, including 500 research scientists, working in the institute. Gov. Gavin Newsom estimated in January that it would take more than three years to fully transform the 700,000-square-foot complex, but Michelson hopes to have a large portion of the immunology institute operating in half that time, he said. At 360,000 square feet, the institute will be the research park’s primary tenant.

The former mall’s 12-screen multiplex movie theater may be converted into lecture halls or performance spaces offering programming across the arts, humanities, sciences and social sciences, the chancellor’s office said.

An interior view of the UCLA research center now under construction in the former Westside Pavilion shopping center.

(Brian van der Brug / Los Angeles Times)

The gift is the Michelsons’ largest single donation in 30 years of philanthropy that includes $50 million to build Michelson Hall at the University of Southern California, which is home to the Michelson Center for Convergent Bioscience. The Michelson name will not be attached to the new UCLA complex, he said, because other philanthropists — perhaps one who donates more than he did — may want the recognition.

“The gift will change countless lives here and across the globe,” UCLA interim Chancellor Darnell Hunt said.

The institute will operate as a nonprofit medical research organization funded by a public-private partnership and governed by an independent board that includes UCLA representatives, according to a UC Regents document. The institute will pay UCLA 7.5% of the net revenues generated by the sale of new medicines and other inventions its scientists create, the document said.

Los Angeles Mayor Karen Bass said the project “has the potential to fundamentally change health outcomes around the world and create good jobs in Los Angeles.”

The purchase of the former Westside Pavilion marked the third major acquisition for the public university system in Los Angeles in less than two years.

Seeking to expand its footprint, UCLA announced in June 2023 it had acquired the Art Deco-style Trust Building in downtown Los Angeles and renamed it UCLA Downtown.

Nine months prior, the school spent $80 million to buy two other major properties owned by Marymount California University, a small Catholic university that was shuttered last year. The purchase included Marymount’s 24.5-acre campus in Rancho Palos Verdes and an 11-acre residential site in nearby San Pedro.

Grocery giants Kroger and Albertsons are facing off against the Federal Trade Commission in federal court, with the two sides fighting over the largest proposed supermarket merger in U.S. history. On Monday, a judge opened a hearing to decide whether to issue a preliminary injunction that would halt the merger plans.

What’s going on?

In October 2022, Kroger and Albertsons announced that they had agreed to merge in a deal valued at $24.6 billion, bringing together Kroger’s vast collection of supermarkets, including the Ralphs chain, and Albertsons’ roster, including the Vons and Pavilions chains.

Kroger and Albertsons say they need to combine in order to better compete with larger, nonunionized rivals such as Amazon, Walmart and Costco. Kroger Chief Executive Rodney McMullen has vowed to use $1 billion in annual savings created by the proposed merger to lower shelf prices, remodel stores and improve worker wages and benefits.

Kroger, based in Cincinnati, Ohio, operates 2,800 stores in 35 states. Albertsons, based in Boise, Idaho, operates 2,273 stores in 34 states. Together, the companies employ around 710,000 people.

What was the reaction to the proposed deal?

Consumer advocates and union representatives quickly decried the proposed merger and urged the government to take a hard look at the potential effects and block the combination. Shoppers, too, voiced concern that a deal would lead to store closures.

What is the FTC’s position?

In February, the FTC issued a complaint seeking to block the merger before an administrative judge.

At the same time, the regulatory agency filed a lawsuit in federal court in Oregon seeking the preliminary injunction. The attorneys general of California, Arizona, the District of Columbia, Illinois, Maryland, Nevada, New Mexico, Oregon and Wyoming all joined the federal lawsuit.

The FTC said the combination of the two supermarket companies would obliterate competition between the major grocers, leading to higher prices and lower-quality products for millions of Americans. It also alleged that the deal would hurt workers, eliminating their ability to negotiate for higher wages and better benefits.

Will my local grocery store be affected if a deal goes through?

Last month, Kroger and Albertsons announced plans to offload 63 supermarkets in California as part of the planned merger.

Those locations, primarily in Southern California, are among hundreds of stores, distribution centers and plants that the companies have proposed selling to another company, C&S Wholesale Grocers, in an effort to allay regulators’ concerns about the mega-merger. Regulators have appeared unswayed that the proposed sell-off, valued at $2.9 billion, would meaningfully change the level of competition in grocery industry.

The 63 California stores listed consist of 15 Albertsons locations, including two in Huntington Beach; 31 Vons locations, including the store on Fairfax Avenue in Los Angeles, as well as the location on West 3rd Street; 16 Pavilions locations; and one Safeway in the Bay Area.

Now what?

A federal district court judge in Portland, Ore., will consider both sides and decide whether to grant the FTC’s request for a preliminary injunction. An injunction would delay the merger while the FTC conducts an in-house case against the deal before an administrative law judge.

Opening remarks by both sides began Monday morning, with the hearing expected to last until Sept. 13. Both sides are expected to appeal if they don’t win.

Tim Massa, Kroger’s chief people officer, said in a statement Monday that the merger would “secure the long-term future of union jobs.”

“Kroger, Albertsons and C&S are committed to honoring all current collective bargaining agreements alongside bargained-for wages and benefits and ensuring zero frontline worker layoffs and no store closures as a result of the merger,” he said. “The only parties that will benefit if this deal is blocked will be the large, non-unionized retailers.”

Times staff writer Suhauna Hussain and the Associated Press contributed to this report.