First National Bank of Southern California, San Marcos Branch Basic Info Reviews Routing Numbers Map & Direction Name: First National Bank of Southern California, San Marcos Branch Main Office: No Service: Limited Service Messenger Office Location: 1110 San Marino Drive San Marcos, California 92069 San Diego County View other branches Phone: 760-471-1051 Please enable JavaScript to view the comments powered by Disqus. Routing NumberProcess ACH TransferProcess Wire Transfer122239021YN122240751YY From: To: