It varies a lot state to state, even area to area. When I moved from STL Co. to Franklin, my rates dropped. When I lived in STL City proper, the rates were so bad I had to stay on a County address (my mom's) just to make it affordable.
I have an insurance broker, have had one for the last ~20 years. He shops around, I've changed insurance companies quite a few times now. They seem to get you on a low price, then slowly raise it and see if it gets noticed. It is a game they play, like cable and internet companies.
Wife and I currently have two Golfs, two Passats, two Ford trucks, and my little camper trailer, all on the bare minimum liability for Missouri, with limited mileage on the Fords and the gasser Passat, and it is fairly inexpensive. We don't crash, and no tickets. I just got the F250 added, and it increased it a whole $7 a month.