Associated Press

NEW YORK — Amazon’s second home could be in an already tech-heavy city, such as Boston, New York or Austin, Texas. Or it could be in the Midwest, say, Indianapolis or Columbus, Ohio. Or the company could go outside the U.S. altogether and set up shop in Toronto.

Those six locations, as well as 14 others, made it onto Amazon’s not-so-short shortlist Thursday of places under consideration for the online retailing giant’s second headquarters.

The 20 picks, narrowed down from 238 proposals, are concentrated mostly in the East and the Midwest and include several of the biggest metro areas in the country, such as Chicago, Washington and Los Angeles, the only West Coast city on the list.

The Seattle-based company set off fierce competition last fall when it announced that it was looking for a second home, promising 50,000 jobs and construction spending of more than $5 billion. Many cities drew up elaborate presentations that included rich financial incentives.

The list of finalists highlights a key challenge facing the U.S. economy: Jobs and economic growth are increasingly concentrated in a few large metro areas, mostly on the East and West Coasts and a few places in between, such as Texas.

Nearly all the cities on Amazon’s list already have growing economies, low unemployment and highly educated populations.

“Amazon has picked a bunch of winners,” said Richard Florida, an economic development expert and professor at the University of Toronto who helped develop that city’s bid. “It really reflects winner-take-all urbanism.”

Among those that didn’t make the cut were Detroit, a disappointment for those excited about progress since the city came out of bankruptcy, and Memphis, Tennessee, where the mayor said the city gave it its “best shot.” San Diego also failed to advance.

“Getting from 238 to 20 was very tough,” said Holly Sullivan, who oversees Amazon’s public policy. “All the proposals showed tremendous enthusiasm and creativity.”

Amazon said it will make a final selection sometime this year.

Besides Austin, another Texas city made the cut: Dallas. In the South, Miami and Atlanta are being considered.

Officials in cities that made the shortlist took the opportunity to further tout their locations, with Philadelphia’s mayor noting “all that Philadelphia has to offer” and officials in and around Pittsburgh citing the region’s “world-class talent pool” and other advantages.

Other contenders among the 20 include Denver; Montgomery County, Maryland; Nashville, Tennessee; Newark, New Jersey; Northern Virginia; and Raleigh, North Carolina.

“It’s a long list for a shortlist,” said Jed Kolko, chief economist at job site Indeed.

He said Amazon may use the list to pit the locations against each other and get better tax breaks or other incentives. Two metro areas, New York and Washington, have more than one location on the list, increasing the competition there, he said.

“It’s hard to say whether all these places are in play or Amazon wanted to encourage continued competition,” Kolko said.

Amazon did not immediately respond to a request for comment on whether locations would be able to change their proposals or offer better incentives, but said in a statement that it will “work with each of the candidate locations to dive deeper into their proposals.”

State and local governments played up the amenities they think make their locations the best choice. Some pulled off stunts to stand out, such as New York, which lit the Empire State Building in Amazon orange.

Some gimmicks didn’t work: Tucson, Arizona, which sent a 21-foot cactus to Seattle, did not make the list. Neither did Birmingham, Alabama, which installed giant replicas of Amazon’s Dash buttons.

The company had stipulated that it wanted to be near a metropolitan area with more than 1 million people, and nearly all of those on the shortlist have a metro population of at least double that.

Amazon also wanted to be able to attract top technical talent; be within 45 minutes of an international airport; have direct access to mass transit; and be able to expand the headquarters to as much as 8 million square feet in the next decade.

But Amazon also made it very clear it wanted tax breaks, grants and any other incentives.

Boston’s offer includes $75 million for affordable housing for Amazon employees and others. Before leaving office Tuesday, Gov. Chris Christie approved a measure to allow New Jersey to offer up to $5 billion to Amazon. Newark is also proposing $2 billion in tax breaks.

But many of the state and local governments competing for the headquarters have refused to disclose the financial incentives they offered. Of the 20 finalists, 13, including New York, Chicago and Miami, declined requests from The Associated Press to release their applications. Toronto’s mayor said Thursday that the city offered no financial incentives to woo Amazon.

Several said they don’t want their competitors to know what they’re offering, a stance that open-government advocates criticized.

Amazon plans to remain in its sprawling Seattle headquarters, and the second home base will be “a full equal” to it, founder and CEO Jeff Bezos has said.

The extra space will give the rapidly growing company room to spread out. It had nearly 542,000 employees at the end of September, a 77 percent jump from the year before. Some of that growth came from Amazon’s nearly $14 billion acquisition last year of the Whole Foods grocery chain and its 89,000 employees.