I - 15 connects Las Vegas to Los Angeles and San Diego , and heads northeast to and beyond Salt Lake City .
Two major freeways -- Interstate 15 and U.S. Route 95 -- cross in downtown Las Vegas .
Interstate 15     connects Las Vegas to Los Angeles and San Diego , and heads northeast to and beyond Salt Lake City .
Two major freeways -- Interstate 15 and U.S. Route 95 -- cross in downtown Las Vegas .