Nearly every Friday and Sunday, a vast stretch of Interstate 15 south of Las Vegas seems to turn into the largest linear parking lot in the West.

It’s been one of the region’s biggest infrastructure challenges for decades. Tourism leaders are mobilizing to solve the traffic problems that plague the primary artery between Southern California and Southern Nevada — and federal spending legislation could provide needed support.

“People have got to be able to get to a location to be able to enjoy what we have to offer,” Rep. Dina Titus, D-Nev., said at the Global Gaming Expo this month. “Here in Nevada, if you go I-15 to Southern California on the weekends, that’s just like a parking lot, there’s so much traffic.”