Cathryn, I think Categories for State Legislatures could be added, but some sort of standardization should be made. I checked in other states under:
http://www.wikitree.com/wiki/Category:US_Politicians
and found a variety of categories relating to State Houses. Most states have no category at all. Others have categories named in different ways, for example:
Maryland State Assembly
New York General Assembly
State Representatives of Minnesota
Montana State Representatives
North Carolina, State Senators
I might suggest that a Category like ____ State Legislature could be created for every state and Categories for state houses would be added under that. As I commented before, for now I still think the best category is just
http://www.wikitree.com/wiki/Category:Michigan_Politicians
I recently edited a prominent Tennessee State Senator and experienced the same problem with Tennessee. I just added her to Tennessee Politicians until some standard categorization is put in place for state legislatures.