The reason is that in 1992 Congress passed the Professional and Amateur Sports Protection Act that banned sports betting in all states except those that already allowed it in some form. What you may not know is that three other States were exempt from the ban because they had some form of legaized sports betting at the time the bill was passed. Those States are Deleware, Oregon and Montana.
OREGON
The State had a lottery games called Sports action. It was run only during football season. The game was similair to the parlay cards bettors pick the outcome of 4 to 14 National Football League games, with the point spreads provided by the lottery, and must win all the games selected to receive a prize. A bet of $1 to $20 can be placed on any one selection of games and there is no limit to the number of entry forms that can be played. The game started in 1989 but in 2005 a bill was signed which ended football wagering at the conclusion of the 2006-2007 NFL season.
MONTANA
The State of Montana allows several types of sports gambling which include sports pools, Calcutta pools, fantasy sports leagues, sports tab games. Calcutta pools are operated similarly to pari-mutuel wagering in that all money wagered on a sporting event is pooled together. Fantasy sports leagues are games in which the participants create fictitious teams assumed to be composed of actual professional athletes. A sports tab game is one in which players purchase a numbered tab (ticket) from a game card containing one hundred tabs with different number combinations. Bettors win money or prizes if their numbers match those associated with a sporting event. The maximum payout for any Montana pool is $500.
DELAWARE
Delaware tried a sports lottery in 1976 based on games of the National Football League (NFL). It was abandoned after only one football season. The State of Delaware is considering allowing wagering on sports at the state's three casinos. If approved, Delaware's sports gambling will not be similar to Las Vegas type gambling. A Delaware sports lottery would mandate that combination bets only would be allowed such as parlays, to keep the original element of chance and make it more difficult to win.