Since the Democrats captured the Pennsylvania House of Representatives in 2022, partisan control has hinged on a succession of special elections. As of this week — following the retirement of a Republican legislator on Friday — the Democrats have a one-seat majority. A special election in the Philadelphia suburbs to fill the seat of a Democratic lawmaker who resigned in December will determine whether that majority grows to two or whether the House is, once again, evenly split.
Source: Elections - nytimes.com