Oak Grove
From Wooljersey
El Sobrante was called "Oak Grove" by industrial concerns in 1887 when the California and Nevada Railroad put a spur into the area for the purpose of carrying lumber cut from the hills. Then the name Sobrante was applied, with the addition of the Spanish definite article "El" coinciding with the opening of the first post office in 1941.
https://en.wikipedia.org/wiki/El_Sobrante,_California#History
