1978Flipped from RepublicanFinal results
1978 election for California Assembly District 30
California State Assembly · California
Jim Costa (D) won with 63.8% of the vote, defeating Octavia Diener (R) by 27.6 points, a seat Republicans won last time.
Jim CostaDemocrat · winner
63.8%41,157
Octavia DienerRepublican
36.2%23,348
64,505 votes
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET
The seat over time
D − R margin in this seat's races around 1978
Races before and after
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET