With absentee votes counted, Ron Roberts gained just over 50 percent of the vote in District 1. Stephen Whitburn had 19 percent and Shelia Jackson 17 percent.
In North County's District 5, incumbent Bill Horn had 46 percent of the vote. Steve Gronke trailed with 21 percent, Tom Bumgardner collected 15 percent and John Van Doorn had 13 percent.
Opponents of both incumbents claimed they were out of touch with the county's electorate after being in office since the mid-1990s.
Whitburn, the head of communications for the American Red Cross in San Diego, and Jackson, a San Diego Unified School District Trustee, both said the supervisors were doing a poor job of funding county services in the down economy.
Gronke complained that Horn is too close with developers. Horn was a backer of the controversial Merriam Mountains project, a 2,700-home development off Interstate 15 that was rejected by his colleagues.
Horn was the last supervisor to have defend his seat in a November runoff, in 1998.