The Zero is a mysterious highway located deep underneath the state of Kentucky.
The entrances to the Zero are hidden and mysterious. Weaver Márquez tells Conway to look for an onramp to the highway at the abandoned Elkhorn Mine. One of the mine tunnels ends only feet from one of the roads of the Zero. Conway and Shannon find an entrance in the barn behind the Márquez Farmhouse after Shannon fixes Weaver's TV.
While entrance may be difficult, it seems that exiting the Zero is quite simple. Exactly how exiting works is unclear; when a surface road is selected from the Zero, the scene simply cuts to the overworld map.
The Zero's roads are so difficult to navigate that, in the recordings of Limits and Demonstrations, Joseph exhorts Lula not to travel them for fear that she won't be able to find her way out.
Conway and Shannon first explore the highway in the hours between Act I and Act II. Going in circles and unable to find Dogwood Drive, they accidentally pull into the Bureau of Reclaimed Spaces. Directed by the receptionist at the Bureau of Reclaimed Spaces and by a brochure from Bureau of Secret Tourism, the two are more capable of navigating the highway.
The highway is depicted as circular, lined with various markers. Depending on where Conway's truck turns around, the highway will change to reveal different markers and topography. The highway must be navigated by turning clockwise and counter-clockwise at the markers, like a combination clock.
Should the player get lost long enough, a small icon will appear in the corner. Clicking this allows Shannon to drive, bringing the truck to the next destination.
Various landmarks, or points of interest, exist inside the Zero. The player can come across various pamphlets from the Bureau of Secret Tourism, which give directions to hidden or unplottable places within the Zero. The destinations can be found, and explored, but never revisited. These small encounters are not required to advance the plot of the game - they merely exist as flavor, and give a bit more insight into the characters themselves. For example, in Act III the player may discover directions to a place called the Rust Archives. When found, the game describes Shannon looking through these Archives, examining strange samples of rust and decay, as if it were a library. This is very mundane and seems pointless, unless the player remembers Lula's offhand comments about her sculpting career, revealing the fate of the sculptures she left behind.
- The Zero may be named as such due to its circular shape. However, the name is also a reference to the traditional naming system of state highways. The American highway system does not use "0" in its number scheme; it begins with US Route 1 on the East Coast and Interstate 2 in central Texas.
- The name may also be related to the concept of zero itself, in mathematical terms, as a value that cannot be physically represented, but is necessary to understand other concepts.
- The notion of supernatural events happening on a highway appears rather often in American fiction. Several episodes of the classic TV show The Twilight Zone feature similar elements (especially "The Hitchhiker," S1 E16). Horror films of the mid-century, like Carnival of Souls (1962), often feature a motorist's accident or detour as an impetus to start the plot, much like Conway's loss of direction at the very beginning of the game.