From Wooljersey

A San Ramon post office with Samuel Russell as postmaster was in place from 1852 to 1859; it was reestablished on December 4, 1873. In 1882, historian J.P. Munro-Fraser wrote that the name “San Ramon” was the one "given to the Post-office at what is usually known as the village of Limerick." Howard Fereira recalled old-timers calling the land south of San Ramon Creek “Limerick” and the area north of the creek “San Ramon.”

Lane, B. (2015). San Ramon Chronicles: Stories of Bygone Days. United States: Arcadia Publishing Incorporated.