Due to the presence of Silicon Valley, the district had[when?] a median household income of $149,375, the second highest of any congressional district in the country.[1][4] After redistricting, the district picked up agricultural areas of Monterey County, and its median household income dropped substantially, to $90,456.
Following the 2020 census and the subsequent 2020 United States redistricting cycle, California lost a congressional district, leading to significant changes across California's districts. Most of the area previously part of the 18th district was split into the new 16th district and 19th district. The 18th district was moved to cover the Salinas Valley in Monterey County and the downtown and east side of San Jose. With the changes, the 18th became a Latino majority district.[5]
As of the 2020 redistricting, California's 18th congressional district was shifted geographically to cover the Salinas Valley. It encompasses San Benito, the southernmost point of Santa Cruz County, and the interiors of Santa Clara and Monterey Counties.
Santa Cruz County is split between this district and the 19th district. They are partitioned by Pajaro River, Highway 129, W Beach St, Lee Rd, Highway 1, Harkins Slough Rd, Harkins Slough, Old Adobe Rd, Corralitos Creek, Varin Rd, Pioneer Rd, Green Valley Rd, Casserly Rd, Mt Madonna Rd. The 18th district takes in most of the city of Watsonville and the census-designated places Interlaken, Amesti, and Freedom.
Santa Clara County is split between this district, the 19th district, the 16th district, and the 17th district. The 18th, 16th, and 19th are partitioned by Bella Vista Ln, Bodfish Creek, Burchell Rd, Bluebell Dr, Day Rd, Highway G8, W San Martin Ave, Santa Teresa Blvd, Sunnyside Ave, Morgan Hill City Limits, Hale Ave, Tilton Ave, Monterey Rd, Highway 101, Coyote Rd, Anderson Lake, Las Animas Rd, Metcalf Rd, Yerba Buena Creek, Old Yerba Buena Rd, Aborn Rd, Quincy Rd, Norwood Ave, Murillo Ave, Pleasant Acres Dr, Westview Dr, Pleasant Knoll Dr, Guluzzo Dr, Flint Ave, Marten Ave, Coldwater Dr, Ocala Ave, Wonderama Dr, Cunningham Ave, Swift Ave, Highway 101, Story Rd, Monterey Rd, Highway 87, Highway 280, Highway 880. The 18th and 17th are partitioned by Steven's Creek Blvd, Di Salvo Ave, Bellerose Dr, Forest Ave, Wabash Ave, W San Carlos St, Race St, The Alameda, University Ave, Elm St, Highway 82, Newhall St, Morse St, Idaho St, Alameda Ct, Sherwood Ave, Hamline St, Highway 880, Highway 101, McKee Rd, Toyon Ave, Penitencia Creek Rd, Canon Vista Ave, Crothers Rd, Alum Rock Park, Sierra Rd, Felter Rd, Weller Rd. The 18th district takes in the center of the city of San Jose and part of the San Jose district of Alum Rock. It also takes in the cities of Morgan Hill and Gilroy and the census-designated places East Foothills and San Martin.
Monterey County is split between this district and the 19th district. They are partitioned by Union Pacific, Highway G12, Elkhorn Rd, Echo Valley Rd, Maher Rd, Maher Ct, La Encina Dr, Crazy Horse Canyon Rd, San Juan Grade Rd, Highway 101, Espinosa Rd, Castroville Blvd, Highway 156, Highway 1, Tembladero Slough, Highway 183, Cooper Rd, Blanco Rd, Salinas River, Davis Rd, Hitchcock Rd, Highway 68, E Blanco Rd, Nutting St, Abbott St, Highway G17, Limekiln Creek, Likekiln Rd, Rana Creek, Tularcitos Creek, Highway G16, Tassajara Rd, Camp Creek, Lost Valley Creek, Lost Valley Conn, N Coast Rdg, 2 Central Coa, Cone Peak Rd, Nacimiento Fergusson Rd, Los Bueyes Creek, and the Monterey County Southern border. The 18th district takes in the cities of Salinas, Soledad, Greenfield, King City, and Gonzales, and the north side of the census-designated place Prunedale, and the census-designated places Aromas (shared with San Benito County), Pajaro, Las Lomas, Boronda, Chualar, Pine Canyon, San Lucas, San Ardo, Lockwood, and Fort Hunter Liggett