California's 4th congressional district consists of all of Lake and Napa Counties, portions of Solano, Sonoma and Yolo Counties. Cities in the district include Clearlake, Lakeport, Middletown, Napa, American Canyon, St. Helena, Dixon, Vacaville, Rio Vista, Cotati, Rohnert Park, Santa Rosa, Sonoma, Davis, Winters and Woodland.
