Nowhere in the U.S. Soccer Federation’s news release Tuesday does it explain why Denver was chosen for the World Cup qualifier March 22 against Costa Rica. One word would sum it up: altitude.

Commerce City, Colo., home to Dick’s Sporting Goods Park, sits at 5,200 feet. Four days later, the Americans will play at Azteca Stadium in Mexico City, which is at 7,300 feet.

There are countless theories about how best to prepare for athletic competition in thin air. Some say it’s smart to arrive either very early or as late as possible. USA Coach Juergen Klinsmann, in consultation with the USSF and the team’s medical and conditioning staff, decided to go up into the mountains and stay there for both qualifiers.

Players will report to camp in Denver after their March 16-17 league games and prepare for the meeting with the Ticos at the 18,000-seat venue in the Denver suburbs. The U.S. team seems likely to remain in Colorado for two days before flying to Mexico City for the March 26 match against El Tri. In all, the U.S. players will be at altitude for nine days, culminating with the Azteca showdown.

The United States did win for the first time at Azteca last summer, but it was just a friendly. The big prize is a victory (or even a draw) in a qualifier. Playing at altitude in the days before the Mexico visit will best prepare the Americans to accomplish that, Klinsmann seems to have concluded.

The question, though, is whether the altitude will have adverse effects on U.S. players arriving from lowland homes, such as England. Altitude is nothing new for the Costa Ricans: San Jose is at 3,800 feet. The possibility of cold weather and snow — it is Denver in March, after all — would be new to the Ticos.

As for the other home qualifiers, the USSF was exploring the possibility of playing June 11 (Panama) and June 18 (Honduras) in the Pacific Northwest, but scheduling issues have complicated matters. Seattle is the MLS’s attendance king, by a wide margin, and Portland is a soccer city with a cozy stadium, but the USSF has been reluctant to play on artificial turf — it’s FIFA legal, but to most players and coaches, not an ideal surface. If the USSF decides to go there at some point, a decision would have to be made whether to play on artificial turf or install temporary grass.

Kansas City and Salt Lake City are also strong contenders for qualifiers as they offer new and small MLS stadiums with strong fan bases. And Columbus is the front-runner for Mexico’s visit in September. (Why change a good thing? “Dos y cero!”) Which leaves the home finale in October against Jamaica: a possible World Cup berth clincher. Is that finally Seattle’s time? Or would the NFL season complicate matters?