[dragonwriter]

> So the official city you live in is not the city that USPS considers you to live in?

Postal addresses have to do with mail delivery and are only loosely associated with political geography.

> If a federal form asks you what city you live in, what do you put down (without committing perjury if there is such a risk)?

The city you live in. See above regarding postal addresses and political geography.

> And how does one figure out what city they officially live in then?

The high latency method is “register to vote, then find out what city’s elections you get ballot material for”. Election authorities can reliably translate postal addresses to electoral districts. (The mappings are publicly available and you can use them directly, but it takes more research to locate them.)

[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.

[mehrdadn]

Wow, I see. Thanks!