Aware of the rising rents, Ms. Bonstin said affordable housing was a priority for the city. “Many projects have a component of affordable housing,” she said, noting that the Weingart Center for the Homeless was putting up two towers that would classify all units as affordable.

Mr. Griffin believes that the growth projections will easily be surpassed, and that downtown could become a city within a city, with as many 200,000 residents in the next 21 years. Already, he said, there are an estimated 70,000, up from 18,000 20 years ago.

“The catalyst for the transformation of Downtown L.A. is the residential development,” said Bert Dezzutti , the executive vice president for the Western region of Brookfield Properties, the district’s largest real estate owner. “Once it establishes itself as a residential destination, it drives the other uses.”

Brookfield has a few developments in the works, including a residential tower next to its Figat7th shopping center, as well as a $170 million overhaul and modernization of the California Market Center in the downtown’s fashion district.

Mr. Dezzutti believes he’ll have little trouble renting out the 780 residential units planned for the high-rise at 755 South Figueroa Street, where construction is set to commence in the second quarter. “The demand is extremely strong, and really there is virtually no appreciable vacancy today.” (By the downtown center BID’s account, it’s under 10 percent.)

A significant portion of the new DTLA development has been driven by foreign investment.

“There’s a high concentration of high-profile property that is foreign owned or developed,” said Michael Soto , the research manager for the Southern California district of the Transwestern Development Company. Mr. Soto, who has been tracking downtown development for more than a decade, said foreign entities “look at L.A. as an attractive place to invest and a gateway city with a diversified economy.”

Duncan Wlodarczak , the chief of staff for the Onni Group of Vancouver, British Columbia, said his company saw untapped value in the downtown when it began looking for potential investments about a decade ago.