USVille

USVille is the town in which all characters in Show live. Its exact location is intentionally left ambiguous, but it's evident they live in the United States, per "A Wolf in Alien's Clothing." More specifically, it is somewhere on the East Coast, as the main characters enter New Hampshire in "A Pointless Episode" following a short amount of driving time. 
It is named for its mayor, US, who needless to say changed it upon becoming mayor, leaving its original name unknown. The population is uncertain, but it can be deduced at least 190 people live in the town (as Deputy Mayor did not dispute the votes at first glance in "Race of the Idiots"). 
A running gag in the series is US' blatant incompetence at performing mayoral duties, even endangering the town on several occasions (see: "What Does She Do, Anyway?," when she mentions the failed "world's largest pizza" experiment that killed some workers). A majority of citizens are often portrayed just as ignorant as she is (there was no library in the town until the above episode), though this varies by episode. It is one of several reasons why NH wants to take over USVille, as he is tired of the stupidity that occurs in the town.
NH mentions in "Why Rack Does Stuff for US" that the town has a bizarre line of succession regarding a situation if the mayor dies in office: whoever is the first to see their deceased body will become the new mayor, forgoing an election. This even applies if the mayor has a deputy. However, in "Race of the Idiots," a general election is held, where NH wins by a landslide and finally becomes mayor. However, it is discovered he committed voter fraud, having voted for himself multiple times. As such, his term is declared null and void with US returning to office.
For a relatively small town, there are a surprising amount of businesses, including several restaurants (both fast food and fancy), convenience stores, Wally World and bakeries. There is also a library (mentioned above), a park for recreational activities and a nursing home, the latter of which Rack works.
==Trivia==
*There are at least three fast food chains in the city: Applebee's, Chili's and Wendy's, the latter most often seen. A fourth, Burger King, was shut down by US for refusing to give her a veggie burger "made from beef."