Southern California - Northern Boundary of Southern California

Northern Boundary of Southern California

"Southern California" is not a formal geographic designation and definitions of what constitutes Southern California vary. Geographically, California's north-south midway point lies at exactly 37° 9' 58.23" latitude, around 11 miles below San Jose; however this does not coincide with popular use of the term. When the state is divided into two areas (Northern and Southern California) the term "Southern California" usually refers to the ten southern-most counties of the state. This definition coincides neatly with the county lines at 35° 47′ 28″ north latitude, which form the northern borders of San Luis Obispo, Kern, and San Bernardino counties. Another definition for Southern California uses Point Conception and the Tehachapi Mountains as the northern boundary.

Though there is no official definition for the northern boundary of Southern California, such a division has existed from the time when Mexico ruled California and political disputes raged between the Californios of Monterey in the upper part and Los Angeles and the lower part of Alta California. Following the acquisition of California by the United States, the division continued as part of the attempt by several pro-slavery politicians to arrange the division of Alta California at 36 degrees, 30 minutes, the line of the Missouri Compromise. Instead, the passing of the Compromise of 1850 enabled California to be admitted to the Union as a free state, preventing Southern California from becoming its own separate slave state.

Subsequently, Californios (dissatisfied with inequitable taxes and land laws) and pro-slavery Southerners in the lightly populated "Cow Counties" of Southern California attempted three times in the 1850s to achieve a separate statehood or territorial status separate from Northern California. The last attempt, the Pico Act of 1859, was passed by the California State Legislature, and signed by the State governor John B. Weller. It was approved overwhelmingly by nearly 75% of voters in the proposed Territory of Colorado. This territory was to include all the counties up to the then much larger Tulare County (that included what is now Kings County and most of Kern, and part of Inyo Counties) and San Luis Obispo County. The proposal was sent to Washington, D.C. with a strong advocate in Senator Milton Latham. However the secession crisis following the election of Abraham Lincoln in 1860 led to the proposal never coming to a vote.

In 1900, the Los Angeles Times defined Southern California as including "the seven counties of Los Angeles, San Bernardino, Orange, Riverside, San Diego, Ventura and Santa Barbara." In 1999, the Times added a newer county—Imperial—to that list.

The state is most commonly divided and promoted by its regional tourism groups as consisting of northern, central, and southern California regions. The two AAA Auto Clubs of the state, the California State Automobile Association and the Automobile Club of Southern California, choose to simplify matters by dividing the state along the lines where their jurisdictions for membership apply, as either Northern or Southern California, in contrast to the three-region point of view. Another influence is the geographical phrase "South of the Tehachapis", which would split the southern region off at the crest of that transverse range, but in that definition, the desert portions of north Los Angeles County and eastern Kern and San Bernardino Counties would be included in the Southern California region, due to their remoteness from the central valley, and interior desert landscape.