Two Septembers figure in shaping the state and county we’re most familiar with today. Beginning in September 1849 delegates met in Monterey, California to create a constitution for a new state to be carved out of the territory won from the war between the U. S.A. and Mexico.

Over the following winter the first state legislature began meeting, and on February 2, 1850, they created the very first California County, San Diego. It’s worth remembering that with transportation of that time limited to foot, horsepower and boats, things like holding conventions and legislatures, not to mention surveying and marking off territorial boundaries, took a lot longer and might not be as precise. Which helps explain why the original San Diego County embraced what are today the counties of San Diego, Riverside, Imperial, San Bernardino and the eastern portion of Inyo County.

That would be the map of San Diego County on September 9, 1850, when California was admitted to the Union as the 31st state.

Sources for this post included San Diego: A Chronological and Documentary History, 1535-1976, compiled and edited by Robert Mayer, and San Diego County, California: A Record of Settlement, Organization, Progress and Advancement, by Samuel F. Black.

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