[umanwizard]

A substantial portion of people do not live in any incorporated city, town, village, etc. This is part of why the concept of census-designated place exists. It's not just a farmer thing -- a lot of what you would consider to be small towns are unincorporated.

Example: Black Canyon City, a small town (arguably becoming a very outer suburb of Phoenix). Population ~5,000 in 2010. Totally unincorporated with no city hall, mayor, or anything like that. https://en.wikipedia.org/wiki/Black_Canyon_City,_Arizona

So I would be surprised if there is any federal form that requires you to put the "city" you live in, outside the context of a USPS address.