The road begins with its western terminus at the California Correctional Institution in Cummings Valley along West Valley Boulevard, its name for part of the route.

The road then abruptly turns north toward SR 58 Business where it is concurrent with the business route through town to its eastern end at State Route 58 with an interchange.

[4] Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage.

R reflects a realignment in the route since then, M indicates a second realignment, L refers to an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see California postmile § Official postmile definitions).

[5] Segments that remain unconstructed or have been relinquished to local control may be omitted.