Traffic.

Traffic, poor traffic engineering, crazy/bad drivers, stop signs at the end of on-ramps to the freeway, toll roads, more cars on the highway at one time than in the entire state of MT.

I will, however, miss the freedom to turn left in front of oncoming traffic if you are the first car stopped at the red light. Maybe I'll try it on Billings people anyway ... they won't know what happened to them!