It is an alternate route of U.S. Route 101 between Arroyo Grande and the city of San Luis Obispo, serving the community of Edna and San Luis Obispo County Regional Airport.

It travels east on Branch St. through the Village, which is the historic downtown section of Arroyo Grande.

The route continues north and enters the city of San Luis Obispo near the airport.

The route turns south onto Higuera St, then west onto Madonna Rd, before it terminates at US 101.

[4] Increasing traffic on the route, especially during peak periods, has required improving capacity on the highway.

It would also require a new alignment for a future connection with SR 1, if that unconstructed portion remains in the route definition.

Because of the terrain between Arroyo Grande and Edna, it was proposed by the county to move the state route to another road which would be easier to expand.

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.