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. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.
^ a bIndicates that the postmile represents the distance along SR 20 rather than SR 45.
^ a bCalifornia Department of Transportation (July 2007). "Log of Bridges on State Highways". Sacramento: California Department of Transportation.
^"Article 2 of Chapter 2 of Division 1". California Streets and Highways Code. Sacramento: California Office of Legislative Counsel. Retrieved February 6, 2019.
^Federal Highway Administration (March 25, 2015). National Highway System: California (North) (PDF) (Map). Scale not given. Washington, DC: Federal Highway Administration. Retrieved October 14, 2017.
^Natzke, Stefan; Neathery, Mike & Adderly, Kevin (June 20, 2012). "What is the National Highway System?". National Highway System. Washington, DC: Federal Highway Administration. Retrieved July 1, 2012.
^ a bCalifornia Department of Transportation. "State Truck Route List". Sacramento: California Department of Transportation. Archived from the original (XLS file) on September 5, 2015. Retrieved June 30, 2015.