Underground

From Achewiki

The Underground is where all the anthropomorphic animals go to conduct their daily business. It has many of the same establishments as the Real World, including several Subway sandwich shops. Entrances to the Underground can be found in sewers and subway tunnels.

In the very early strips the characters were mainly confined to 62 Achewood Court and forced to trick humans if they wanted any goods or services. Rather quickly this was dropped as it was quite limiting. The Underground provided a way for them to interact with regular American culture (have jobs, complain about the cost of CDs, &c) while still only interacting with other animals. Whenever a character mentions going to a place of business (Taco Bell, The Smoke, Laszlo's, &c) it is assumed they mean the Underground version unless otherwise stated.

The Achewood Underground is connected to Undergrounds in other cities via the National Subterranean Transit Link (NSTL).