2008Final results
2008 election for Pennsylvania House District 21
Pennsylvania House of Representatives · Pennsylvania
Dominic James Costa (D) won with 78.7% of the vote, defeating Dan Mahon (Ind) by 64.6 points.
Dominic James CostaDemocrat · winner
78.7%20,650
Dan MahonIndependent
14.1%3,695
7.2%1,891
26,236 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 2008
Races before and after
Source: Harvard Dataverse / Carl KlarnerUpdated Sep 30, 2026, 7:29 AM ET