An American bid for the 2024 Summer Olympics would come from Boston, Los Angeles, San Francisco or Washington if the U.S. Olympic Committee decides to put a city in the running.

A USOC process that began 16 months ago by sending letters to leaders in 35 cities is now at four finalists after Dallas and San Diego were scratched from the list of possible bidders.

Los Angeles hosted the 1932 and 1984 Olympics. Boston, San Francisco and Washington would be first-time hosts.

“Boston, LA, San Francisco and Washington have each given us reason to believe they can deliver a compelling and successful bid, and we look forward to continuing to explore the possibilities as we consider 2024,” USOC CEO Scott Blackmun said.

But there’s an arduous and expensive process facing any potential bid city before the International Olympic Committee awards the Games in 2017.

Over the next six months, the USOC will decide whether it even wants to try to host the Olympics. The last two U.S. candidates both suffered humiliating fourth-place finishes: New York for the 2012 Olympics and Chicago for the 2016 Games that went to Rio de Janeiro

Unlike the public, and sometimes embarrassing, domestic bid process for the 2016 Games, the USOC kept a tight lid on the group of cities under consideration in order to have more candid conversations and save money.

Still, some cities didn’t make the cut. San Diego was always a long shot because of its smaller size. Dallas got in the game early but weather issues and some lingering bad memories of America’s last foray into a Southern city — Atlanta — put roadblocks in front of that bid.

“Dallas had a great bid and matching leadership, along with a well-established sporting community,” USOC chairman Larry Probst said. “We have no doubt about the ability of Dallas to host the Olympic and Paralympic Games, and look forward to working with them in the future to enhance the international awareness of the city.”

If the USOC goes ahead with the bid, the U.S. city chosen would find itself in a competitive fight. Paris, Rome, Doha and Istanbul are among those that could enter the race. The IOC has also long stated a desire to bring the Olympics to Africa for the first time.

Some inside the USOC feel the time is right for a bid, now that the federation has made progress in shoring up some of its international relationships, which were frayed in 2009 when Chicago finished last in the voting for the 2016 Games.

The USOC is waiting to see what sort of changes the IOC might make in the bidding process when it meets later this year. New IOC president Thomas Bach is asking the committee to build a new roadmap for the Olympics, and the way the IOC handles bids is expected to be on that agenda.