It'll carry Mexican produce north, put rural towns on the map and transform isolated cities into transportation hubs. But though funding for Interstate 11 is non-existent and construction still decades away, opposition to the Mexico-to-Canada corridor – the first new interstate since I-70 was completed in 1992 – is already gathering steam. "We know freeways drive development and sprawl," says Sandy Bahr, director of the Sierra Club's Grand Canyon chapter. "And we already have huge air-quality problems in the Phoenix area."

Or, as Tonopah, Nev., business owner Ron Browning grumbled to the Las Vegas Review-Journal, "By the time they get a freeway built, we'll be flying cars."

A section linking Phoenix and Las Vegas – the largest adjacent major U.S. cities not joined by an interstate – is the top priority, with planning underway. Supporters cite economic benefits, safer driving and decreased traffic jams. But along less-developed routes north of Vegas and south of Phoenix, the response is less enthusiastic. In Picture Rocks, Ariz., retiree Albert Lannon enjoys sleeping on a futon outside his doublewide, listening to great horned owls. "I'd hate to listen to the sounds of traffic instead," he says.

SOURCES: Nevada Department of Transportation, Las Vegas Review-Journal, i11study.com