The term "SLO" is a historical and commonly used reference for the county and its county seat, San Luis Obispo, initials as well as a description of the region's relaxed culture.[7]
According to the U.S. Census Bureau, the county has a total area of 3,301 square miles (2,113,000 acres) of which 3,299 square miles (2,111,000 acres) is land and 317 square miles (820 km2) (comprising 8.8%) is water.[4][8] San Luis Obispo county is home to some of California's coolest winemaking areas similar to climatic influences as its northern counterparts, Napa and Sonoma counties.
The proximity of the Pacific coastline to the viticultural areas of San Luis Obispo Coast (SLO) Coast, and at the county's southern end, Arroyo Grande Valley, influences their vineyards to the cool marine air.
The county is home to sixteen distinctive viticultural areas (AVA) including the spacious Paso Robles with its eleven sub-region AVAs, the diminutive neighbor, York Mountain and the elongated newcomer, San Luis Obispo (SLO) Coast.
^"§ 4.25 Appellations of Origin"(Title 27: Alcohol, Tobacco and Firearms; Part 4 — Labeling and Advertising of Wine; Subpart C — Standards of Identity for Wine). Code of Federal Regulations. Retrieved January 4, 2008. This article incorporates text from this source, which is in the public domain.
^"The TTB Story". TTB.gov. Alcohol and Tobacco Tax and Trade Bureau, Treasury. 2002. This article incorporates text from this source, which is in the public domain.