Fulton is a census-designated place (CDP) in Sonoma County, California, United States. Fulton is just to the north of the city limits of Santa Rosa, and 7 miles (11 km) north-northeast of Sebastopol. Fulton has a post office with ZIP code 95439, which was established in 1871. The community is named after Thomas and James Fulton, who founded the community. The population as of the 2010 U.S. Census was 541. There are a set of railway lines which go through the town boundaries; these lines are used by Sonoma–Marin Area Rail Transit (or the SMART Train).