Sometimes you may want to see just ONE county with the cities also shown. For that purpose, here’s a list of ALL U.S. Counties with City Limits:
For example, here is Sacramento County, California: Sacramento County, California – County Map with Cities
You get a map like this:
If you’re looking for historical county maps, you can use the interactive Historical U.S. Counties map tool or see a listing of all Historical U.S. County Maps by state by year.