Route description
SR 175 connects U.S. Route 101 at Hopland to State Route 29 near Lakeport through the Mayacamas Mountains. From there it joins SR 29 until Kelseyville, where it loops out until meeting SR 29 again at its end at Middletown. The section between Hopland and Lakeport is also known locally as the "Hopland Grade", or "Hopland Pass."
Except for the portion on SR 29, SR 175 is not part of the National Highway System,[3] a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration.[4]
History
Originally constructed in the early 1920s, it is one of the steepest and most difficult to drive of any California state highway. Until recently it was called the "crookedest road in California".[citation needed] Vehicles more than 39 feet (12 m) in length are banned from the Hopland Grade, due to its many tight hairpin turns and curves.[2]
Major intersections
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 b Indicates that the postmile represents the distance along SR 29 rather than SR 175.
US 101 at Hopland
SR 29 from near Lakeport to near Kelseyville
