You've maybe heard of the Curse of the Goat that prevents the Cubs from winning a World Series.
The Curse of the Babe kept Boston out of the title form 86 years.
Here's some newer curses:
1) The Curse of Marty Schottenheimer. Go 14-2 and get fired = curse. Downhill slide after Marty activated the curse. It will stay in place until there is a new owner and new GM.
2) Curse of Mike Shanahan....no Super Bowl victories for the Raiders. Curse in place 21 years now. It will last until Davis pays the money still owed to Shanahan or Davis dies.
3) The curse of Eddie....10 years running. No relief until Eddie D gets his 49ers back.
Add those up and a California team may never again win a Super Bowl.
Other states: Even though the Cowboys snuck in a Super Bowl after Jimmy left, once he activated the curse - 15 years now and only one playoff win.