UPDATE: At 5:25 p.m., the back up was down to 9 miles.
If you need to get back to California today, it could take a while.
Some drivers were not expecting such a large back up after the holiday celebrations.
“Not like this, usually when you get out of the California traffic it’s usually a straight shot. But man, this is a little daunting because there’s basically one highway that gets us back down there, so we’ll see what happens," said Matt Balk, who was trying to get back to Huntington Beach, CA.
At 1 p.m. Monday, traffic was backed up for 16 miles on Interstate 15 southbound according the Regional Transportation Commission.