The joint North American bid is seen as the favorite for 2026, with only one other bid -- Morocco -- so far in the running for the tournament.
A list of 41 potential host cities -- in the running to stage matches or host teams -- had been circulated last month by organisers.
That number was trimmed down to 32 after nine cities including Cleveland, Pittsburgh, San Antonio and New Orleans were excluded from consideration.
"As we move to the next stage of the bid process, we're even more confident we have everything needed to deliver the largest, most compelling FIFA World Cup in history and help accelerate the growth of soccer across North America and around the world," bid chairman Sunil Gulati said in a statement yesterday.
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"We have more than double the number of cities required to stage matches in 2026. We have a vision for growing the game and engaging fans as never before."
Cities not hosting games could be chosen as other venues needed for the tournament, such as team base camps.
Bid officials have said 60 of the tournament's matches would be staged in the United States, with Canada and Mexico hosting 10 games each.
The United States will host all knockout games from the quarter-finals onwards.
Stadiums under consideration in the United States include several venues used in the 1994 World Cup, including the Pasadena Rose Bowl.