Map of the counties of California as they appeared between 1963 (when the zigzag between Kern and San Bernardino was created) and 1991 (when a chunk of northeast Ventura was given to Kern). Note that the Newberry Library lists a number of other boundary changes in that time period, but all save one were two small for their interactive map, much less our purposes. The one relatively big change in the period was the 1988 addition of two kinks in the Orange-Riverside boundary that are so small that they weren't included in this map to begin with.
This file was derived from: California county map, cb 500k.svg Redrawn county lines informed by The Newberry Library
Original work by User:Awmcphee. This version by User:WallAdhesion.