Here's Sullivan's detailed descriptions of each region, The 10 Regions of US Politics.

"Our regions are based on voting returns from both national and state elections, demographic data from the US Census, and certain geographic features such as mountain ranges and coastlines. Each region represents about one-tenth of the national electorate, casting between 10.4 million and 10.8 million votes in the 2000 presidential election. "

San Francisco is part of Upper Coasts.

"The communities in Upper Coasts are known for both civic responsibility and civil disobedience. This two-part region is anchored in the east by Boston and in the west by San Francisco, but both cities tilt decidedly to the left. "