Super Bowl Preparations

The Super Bowl is in Santa Clara, CA this year.  I believe Santa Clara is about two hours from San Francisco.  Why are all the festivities taking place up here?  Getting around by foot, car, public transportation, et al are very difficult.  Super Bowl preparations appear to be taking place all over the city.  Major streets have been closed to cars and pedestrians.  Pedestrians too?  I might go out of town to avoid the chaos.