thumb|upright|right|The entrance lobby and belfry of the Mission San Luis Obispo de Tolosa. A statue of Fray Junípero Serra stands outside the church.
thumb|[[Robert Jack House, built c. 1882]]
San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 United States census, the population was 282,424. The county seat is San Luis Obispo.
Junípero Serra founded the Mission San Luis Obispo de Tolosa in 1772, and San Luis Obispo grew around it. The small size of the county's communities, scattered along the beaches, coastal hills, and mountains of the Santa Lucia range, provides a wide variety of coastal and inland hill ecologies to support fishing, agriculture, and tourist activities.
California Polytechnic State University has almost 20,000 students. Tourism, especially for the wineries, is popular. Grapes and other agriculture products are an important part of the economy. San Luis Obispo County is the third largest producer of wine in California, surpassed only by Sonoma and Napa counties. Strawberries are the largest agricultural crop in the county.
The town of San Simeon is located at the foot of the ridge where newspaper publisher William Randolph Hearst built Hearst Castle. Other coastal towns (listed from north to south) include Cambria, Cayucos, Morro Bay, and Los Osos -Baywood Park. These cities and villages are located northwest of the city of San Luis Obispo. To the south are Avila Beach and the Five Cities region. The Five Cities originally were: Arroyo Grande, Grover Beach (then known as Grover City), Oceano, Fair Oaks and Halcyon. Today, the Five Cities region consists of Pismo Beach, Grover Beach, Arroyo Grande, Oceano, and Shell Beach (which is actually part of Pismo Beach), i.e., essentially the area from Pismo Beach to Oceano. Just south of the Five Cities, San Luis Obispo County borders northern Santa Barbara County. Inland, the cities of Paso Robles, Templeton, and Atascadero lie along the Salinas River, near the Paso Robles wine region. San Luis Obispo lies south of Atascadero and north of the Five Cities region.
History
The prehistory of San Luis Obispo County is strongly influenced by the Chumash people. There has been significant settlement here at least as early as the Millingstone Horizon thousands of years ago. Important settlements existed in coastal areas such as Morro Bay and Los Osos.
Mission San Luis Obispo de Tolosa was founded on September 1, 1772, in the area that is now the city of San Luis Obispo. The namesake of the mission, city and county is Saint Louis of Toulouse, the young bishop of Toulouse ("Obispo de Tolosa" in Spanish) in 1297.
San Luis Obispo County was one of the original counties of California, created in 1850 at the time of statehood.
The Salinas River Valley, a region that figures strongly in several John Steinbeck novels, stretches north from San Luis Obispo County.
Geography
thumb|right|San Luis Obispo
thumb|right|Sand dunes - Oceano CA
right|thumb|Morro Bay Docks
According to the U.S. Census Bureau, the county has a total area of , of which is land and (comprising 8.8%) is water.
Climate
thumb|Köppen climate types of San Luis Obispo County, California, using 1991–2020 climate normals. San Luis Obispo County has three main climate types. BSk climate can mainly be found in the eastern portions of the county, along with certain smaller areas in the north. Csa climate can mainly be found in the central portions of the county, in communities such as Paso Robles. The rest of the county is made up of the Csb climate type. The Csb warm-summer mediterranean type climate together with the county's varied landscapes reminds visitors of European locales.
Adjacent counties
National protected areas
- Carrizo Plain National Monument (part)
- Guadalupe-Nipomo Dunes National Wildlife Refuge (part)
- Los Padres National Forest (part)
Marine protected areas
thumb|[[Piedras Blancas State Marine Reserve and Marine Conservation Area, an elephant seal rookery.]]
- Cambria State Marine Conservation Area
- Chumash Heritage National Marine Sanctuary
- Monterey Bay National Marine Sanctuary
- Morro Bay State Marine Recreational Management Area and Morro Bay State Marine Reserve
- Piedras Blancas State Marine Reserve and Marine Conservation Area
- Point Buchon State Marine Reserve and Marine Conservation Area
- White Rock (Cambria) State Marine Conservation Area