They aren't even using the college stadiums like the Big House or Stanford this time.
....
Stanford Stadium was torn down and rebuilt, at a much smaller capacity, after the 2005 football season. It's effectively a totally new stadium that seats at least 30,000 fewer than the the old one did.
I was speculating the other day on whether it would be possible for the US, or the US and Canada co-hosting, to hold a World Cup entirely at indoor stadiums, assuming for discussion purposes that every stadium owner were willing to participate, that every venue could meet FIFA's field-width requirements, and every city were willing to agree to the hosting agreement. I concluded that for this year it would have been tight (I counted 15 possible stadiums) but that for the 2031 Women's World Cup, which is supposed to have 48 teams, it would be possible. (I've excluded Mexico because I don't believe they have any indoor stadiums.)
Cities with existing indoor stadiums of sufficient capacity: Vancouver, Inglewood (LA), Glendale (Phoenix), Las Vegas, Arlington (Dallas), San Antonio, Houston, New Orleans, St. Louis, Minneapolis, Detroit, Indianapolis, Atlanta, Syracuse, and Montreal. (That's 15.) I don't include Toronto on the list because SkyDome's seats have been permanently locked in baseball configuration, which is one reason why this year's World Cup games are being played at BMO Field instead.
Upcoming indoor stadiums: Nashville (opening this year), Cleveland (targeting 2029), and DC (targeting 2030). The Chiefs' new dome in Kansas is estimated for 2031, so I wouldn't count that one as a possibility for the Women's World Cup.
So that's 18 stadiums, again assuming all of them were eligible and the owners/localities were willing.