| State Route System | |
|---|---|
   Highway markers for SR 3, SR 17, and SR 157 | |
 Map of Alabama State Route System | |
| Highway names | |
| Interstates | Interstate nn (I-nn) |
| US Highways | U.S. Route nn (US nn) |
| State | State Route nn (SR nn) |
| System links | |
| |
The State Route System in Alabama uses the standard numbering convention: odd numbers signify a north–south state route, and even numbers signify an east–west route. Often more than one route number shares the same roadway, so identifying which route the mile markers are for is often difficult.
In no case does a state route number mirror a U.S. Highway number. As such, the following state routes do not exist: 11, 29, 31, 43, 45, 72, 78, 80, 82, 84, 90, 98, 231, 278, 280, 331, 411, or 431.