I'm a Diaspora Armenian-American, with Swiss & Armenian Ancestgry.
The 2010 California Census indicates that there are 600,000 Diaspora Armenians in California. It's probably a low estimate, because assimilated Armenians frequently go unnoticed, including half blooded Armenians like myself, who still feel loyal to the Armenian Highlands.
The first significant settlement of Armenians, in California, was in Fresno, during the 19th Century. California's Armenian Diaspora grew rapidly after the Hammidian Massacres (1894 - 1896), Adana Massacre (1909), and Armenian Genocide (1915 - 1923).
Southern California has the largest Armenian Diaspora, especially Glendale & the greater Los Angelos Area.
I live in the San Francisco Bay Area. Churches in the SF Bay Area include the Saint John Armenian Apostolic Church, Saint Gregory Armenian Apostolic Church, and Calvary Armenian Congregational Church, in San Francisco; the Saint Vartans Armenian Apostolic Church, in Oakland; and, the Saint Andrew Armenian Apostolic Church, in Cupertino, near San Jose.