Unsurprisingly, San Francisco County data shows the highest number of gay and lesbian couples in California according to demographic census analysis by the Williams Institute.

What may or may not be surprising though, is that California ranks fourth in the nation at 7.8 couples per 1000.  First is the District of Columbia at a staggering 18.08 couples per 1000.

See Institute reports same-sex couples by county | Politics Blog | an SFGate.com blog.