One is a spot near Gerber in Tehama County, which is marked by a large obelisk. The California Geographic Survey placed the obelisk at the center of the state in 1931, based on the state’s boundaries at the time. In case you’re curious, the obelisk is located between the cities of Chico and Red Bluff, at 39.833 N, -122.367 W.
However, the US Geological Survey recalculated the center of California after the state annexed a small piece of land in the southeast corner, near Blythe, in 1857. By their math, the center of the state is actually about ten miles to the south of Gerber, near Black Butte Lake, at 38.52 N, -119.01 W.