With legal sports betting spreading throughout the U.S., this year's Super Bowl could be among the most bet-on championship games ever. And while many fans are old hats at betting on the football, Sunday's game will be only the second since a U.S. Supreme Court ruling that opened the door for all 50 states to offer legal sports betting. So far, sports betting is available in 14 states. The most popular bets continue to be on the point spread and the over/under. There are also numerous prop bets people can make on things that happen during the game.