You guys are all too funny, the silverdome is still there #1. A guy bought it for $500,000 and still runs events there. It cost millions to build and he got a steal on it, but what are you gonna do with a stadium????
#2 - Why have 3 in Anaheim? Because they sell out all 3 of them, have 3 different tracks, and all of the industry is based close by and let's face reality. The economy of the Southern Cali area is in better shape than Detroit's economy. The teams are all based there, the aftermarket is mostly based there, and the riders are mostly based there for the winter anyway..... and advertising sells the show by sponsors paying the way. I bet that they can get twice as much ad revenue in Anaheim than they can in Detroit. Unfortunately, Ohio might be the most important state in a presidential election, but it's not in the SX choice of where to hold races.
Make a vacation out of 1 and go hang out for a weekend out there. You'll see why they go there instead of Detroit in the winter.