State Route 53 (SR 53), also known as the Clearlake Expressway for part of its length, is a state highway in the U.S. state of California that runs in a north–south direction in Lake County east of Clear Lake, It connects SR 29 and SR 20 via the city of Clearlake.

SR 53 begins at California State Route 29 in the town of Lower Lake, near Anderson Marsh State Historic Park, primarily as a four-lane divided semi-rural expressway.

Once it crosses Lakeshore Drive, it narrows down to a two-lane highway until its northern terminus at California State Route 20 north of the city limits.

[7] 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.

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