Mark James DeSaulnier ( ; born March 31, 1952) is an American politician who has served as the U.S. representative for California's 10th congressional district since 2015 (known as the 11th congressional district until 2023). The district includes most of Contra Costa County, a suburban county in the East Bay. He has been a member of the Democratic Party since 2000; before that, he was a Republican. Before serving in the House of Representatives, DeSaulnier was a member the Concord City Council (1991–94), a Contra Costa County Supervisor (1994–2006), and a member of the California State Legislature, representing the 11th State Assembly district from 2006 to 2008 and the 7th State Senate district from 2008 to 2015. Early life and education DeSaulnier was born in Lowell, Massachusetts, to Edward Joseph DeSaulnier Jr. and Virginia Ann DeSaulnier (née Burke). He was raised in a Roman Catholic family. He earned a Bachelor of Arts in history from the College of the Holy Cross. After his father, a Massachusetts Superior Court judge, became involved in a scandal in the early 1970s, DeSaulnier relocated to California, settling in Concord. He worked as a probation officer, truck driver, and hotel services employee. He later owned and operated several restaurants in the San Francisco Bay Area. Early political career Concord politics DeSaulnier was appointed to the Concord Planning Commission in 1988. In 1991, he was elected to the Concord City Council and served as mayor of Concord in 1993. He was also a member of the University of California Toxic Substances Research and Teaching Program Advisory Committee. Contra Costa County Board of Supervisors In early 1994, Governor Pete Wilson appointed DeSaulnier, then a fellow Republican, to the Contra Costa County Board of Supervisors, filling a vacancy caused by the resignation of Supervisor Sunne McPeak. He was elected in 1994 and reelected in 1998 and 2002. In 1998, he received 98.4% of the vote against write-in candidates. In 2002, he received 79% of the vote against challenger Dione Mustard. During DeSaulnier's tenure on the Board of Supervisors, he sponsored the Industrial Safety Ordinance and the Refinery Flare Rule for local refineries and chemical facilities. He served on the executive boards of the Association of Bay Area Governments, the Bay Area Air Quality Management District and the Metropolitan Transportation Commission. He was appointed to represent the Bay Area on the California Air Resources Board by the Air District