Ramp Volume Index for Caltrans Districts and associated counties
District 1 = Del Norte; Humboldt; Lake; and Mendocino Counties.
District 2 = Lassen; Shasta; Siskiyou; and Tehama Counties.
District 5 = Monterey; San Benito; San Luis Obispo; Santa Barbara; and Santa Cruz Counties.
District 6 = Fresno; Kern; Kings; Madera; and Tulare Counties.
District 7 = Los Angeles and Ventura Counties.
District 8 = Riverside and San Bernardino Counties.
District 9 = Inyo and Mono Counties.
District 10 = Merced; San Joaquin; and Stanislaus Counties.
District 11 = Imperial and San Diego Counties.
Those Counties not listed within a Caltrans District above, do not have freeway ramps. They include: Alpine; Amador; Calaveras; Mariposa; Modoc; Plumas; Sierra; Trinity; and Tuolumne.