4 charts show how fast everyone is flocking back to big cities

The outflow of residents from cities to suburbs and exurbs has slowed for permanent movers, and cities are once again growing. Urban population growth was steady across all metropolitan areas tracked by UBS.

That uptick is a "positive trend" for cities after several months of plunging occupancy, the team said. Still, it'll take months for urban areas to return to their pre-crisis density. The speed of that rebound depends on when large-scale employers call workers back to offices, and how many workers who left cities are willing to return, the economists said.

Temporary mover data signal the shift from cities to suburbs and exurbs has almost entirely ended. The return to trend is most likely fueled by companies' return-to-office efforts.

While promising for cities looking to recoup residents, the recent uptick in virus cases presents a new hurdle for their recoveries. Daily case counts are now the highest since January as the Delta variant of COVID-19 spreads across the US. A return to partial lockdowns could revive the out-migration seen last year.

It's possible New York City will be the first city to stage a full recovery in occupancy, as residency began climbing in late May, according to UBS. At the same time, suburbs, towns, and rural areas started to lose residents in late February.

The rebound is likely a product of financial firms and major banks having some of the strictest return-to-office policies, analysts at Jefferies said in a July 25 note. The push for in-person work fueled a "scramble for apartments" and put New York City in the lead among major US metropolitan areas regaining occupants, they added.

California cities show similar trends but aren't as far along in their rebounds. While out-migration has slowed markedly in cities, they're still losing residents, according to UBS. Meanwhile, population growth remains mostly flat in rural areas and towns.

The gap between New York and California cities' recoveries likely has to do with their different return-to-office strategies, Jefferies analysts said in July. While finance giants mandated in-person work early in the summer, the tech giants of Silicon Valley have pushed back their calls to return to offices as virus cases surge higher. New York City saw occupancy grow on net in May and June, according to Jefferies. Conversely, population growth was flat in San Francisco and remained negative in Silicon Valley over the same period.

Virus case counts have only soared higher since change-of-address data was last updated. Should infection trends hold, the split between east- and west-coast cities could power a sharp divergence in how urban economies recover.