CA Congressional District 6, Marin & Sonoma.
From Wikipedia:
California's 6th congressional district stretches up the Pacific coast north of San Francisco Bay. It covers Marin County and most of Sonoma County, including the cities of Santa Rosa, Rohnert Park, Petaluma, Novato, San Rafael, and Mill Valley. This district is currently represented by Democrat Lynn Woolsey. Before her, it was represented by Barbara Boxer, who resigned from the seat when she was elected to the U.S. Senate.