Democrats declared victory in three races Tuesday night for Delaware County's five-member council, sweeping Republicans entirely from what had been an all-Republican panel just a couple years ago.
With a substantial lead over their Republican opponents, Monica Taylor, Elaine Paul Schaefer and Christine Reuther all claimed victory on Tuesday night.
Long a bastion of Republican support, Philadelphia's heavily populated suburbs are becoming increasingly liberal, a trend that has accelerated since Donald Trump's election as president.
The race for Delaware County District Attorney is still too close to call. Republican District Attorney Katayoun Copeland was trailing slightly being Democrat Jack Stollsteimer as of 12 a.m. Wednesday.
Democrats were also fighting for control of Bucks County's board of commissioners, where they last had control for four years in the 1980s.
In Chester County, Pennsylvania, Democrat Deb Ryan had a strong lead over Republican Michael Noone as of 12 a.m. Wednesday.
--The Associated Press contributed to this report.