The 1st Supervisorial District is bounded on the north by Franz Valley School Road, the Napa county line to the east, to the west by Petaluma Hill, Summerfield, Brush Creek, Wallace & Riebli Roads, & San Pablo Bay to the south.
Population is concentrated in the City of Santa Rosa (Bennett Valley, Rincon Valley & the community of Oakmont), the City of Sonoma and the adjacent unincorporated communities of Kenwood, Agua Caliente, Glen Ellen, El Verano, Boyes Hot Springs, Schellville & Vineburg.