All the unincorporated places I'm familiar with in the mainland US are under the jurisdiction of federal, state and county governments, but not a city or town g

All the unincorporated places I'm familiar with in the mainland US are under the jurisdiction of federal, state and county governments, but not a city or town government. I'm sure there are examples of more sovereign towns... US Postal Service is federal and required to service the whole country. Lots of cities and towns manage utilities like power, sanitation, etc. and would probably exclude unincorporated properties from access. People just buy them from county governments, private companies, etc.