California's Coastal Zone generally extends seaward to the state's outer limit of jurisdiction, including all offshore islands, and inland to approximately 1,000 yards from the mean high tide line (MHTL) of the sea, or in significant coastal estuarine, habitat, and recreational areas to the first major ridgeline paralleling the sea or five miles from the mean high tide line of the sea, whichever is less. In developed urban areas the zone generally extends inland less than 1,000 yards.

Public Resources Code (PRC) Section 30103(a) specifically defines California's Coastal Zone as that land and water area of the State of California from the Oregon border to the border of the Republic of Mexico depicted on maps identified and set forth in Section 17 of that chapter of the Statutes of the 1975-76 Regular Session enacting PRC Division 20 (the Coastal Act of 1976). PRC Section 30103(b) directed the Coastal Commission to prepare and adopt more detailed 1:24,000 scale Coastal Zone Boundary (CZB) maps, which occurred March 1, 1977. These 161 adopted maps provide the official basis for all other representations of the landward CZB. The digital version of the CZB created by developing this shapefile is a conformed copy of the official boundary, however, it has not yet been adopted by the Coastal Commission, and as such, does not yet supersede the boundary adopted in 1977 and amended and adjusted from time to time since then.