If you have property in multiple states, you should have a trust.
However, you do not need a trust for each state.
Much as one can be a Delaware Corporation, even though one has never set foot in the state of Delaware, you can choose which state's law you want to govern the terms of your trust. So you can have a California trust that owns property in Texas, Pennsylvania, and Washington.
The key, though, is to have a trust. If you do not have a trust and you have real estate in different states, you may be forced to do a probate in each state that you own real estate in, which is very expensive and very time-consuming. You may also want to consult with a lawyer in the relevant jurisdictions to review your unique situation.