Since the state is broken up into counties, and each county subdivided into precincts, this provides a natural way to form cluster samples.
If the precinct populations are too large, then you can further subdivide based on household or building residence. In other words, you can randomly select a building and consider that a separate cluster. All residents of that building would be part of the cluster.
In cluster sampling, the idea is that whichever clusters you select, you survey every person who resides in that cluster. So naturally you need to be careful not to go overboard.