EDITOR'S NOTE: LehighValleyNews.com is partnering with student journalists of The News Lab at Penn State on reporting about the upcoming election through Election Day.
UNIVERSITY PARK, Pa. — In Westmoreland County, Pa., a quiet political transformation tells a story that national headlines have missed. Since 2016, nearly 40,000 voters have shifted from Democratic to Republican registration — a margin that represents almost half of President Joe Biden's entire winning gap in Pennsylvania in 2020.
This dramatic flip isn’t an isolated incident. While most are focused on understanding traditional swing counties, Pennsylvania is seeing a "seesaw effect" reshape its political landscape. Twelve counties that held Democratic majorities in 2016 are now Republican-majority. One county flipped from Republican to Democratic. And in seven counties, including Philadelphia, a significant number of voters are abandoning both major parties altogether.
These shifts, captured in Pennsylvania's latest voter registration data, released after the Oct. 21 deadline, suggest the presidential race won't be decided by which candidate wins these counties — but by their margins of victory. With 19 electoral votes hanging in the balance, the margins across each of the 13 seesaw counties could make all the difference.
The News Lab's analysis has identified 13 seesaw counties worth watching on Election Night, each telling a different story about Pennsylvania's evolving political landscape.
Election Night counties to focus on
Between 2016 and 2024, several counties saw a shift in voter registration from one major party to another.
Twelve counties — Beaver, Bucks, Cambria, Carbon, Elk, Fayette, Greene, Luzerne, Lawrence, Mercer, Washington and Westmoreland — were majority Democrat in 2016 and are now majority Republican.
Cambria, Mercer, Washington and Westmoreland counties saw the most dramatic shifts.
In the span of eight years, Cambria County went from a Democratic majority by 12,622 to a Republican majority by 15,153. That’s a difference of 27,775 voters.
Over the same period, Mercer County’s Democratic majority of 1,049 shifted to a 14,014 Republican majority — an overall difference of 15,063.
A similar seesaw effect can be seen in Washington County. Registered Democrats had a 12,719 lead during the 2016 election year, but registered Republicans now have a 17,514 registered voter lead. That’s a difference of 30,233.
Westmoreland County, however, experienced the most dramatic flip. Republicans jumped from 103,712 to 131,917 registered voters in eight years. That’s an increase of 28,205, the largest of any county in Pennsylvania. In total, it’s a margin of 40,670.
Chester County was the only county in Pennsylvania to shift from a Republican majority in 2016 to a Democrat majority of registered voters in 2024. The county’s registered Republicans had a lead of 18,468 eight years ago, and registered Democrats now lead the county by 6,047.
These counties display a clear, but unusual trend across the Commonwealth — nearly twenty percent of counties have seesawed politically, as far as registrations are concerned, since 2016. Only election day will tell just how this seesaw affects voter turnout and the margins-of-victory.
Registered as blue voters, acting as red
In 2016, Beaver, Cambria, Erie, Luzerne, Northampton, Washington and Westmoreland counties voted Republican despite having a Democratic majority of registered voters. Beaver and Luzerne repeated this in the 2020 election.
Erie in particular had 30,103 more registered Democrats than Republicans in 2016. Despite this, Trump won by 1,957 votes.
‘Other’ voters: Different parties, different people, still important votes
As a Pennsylvania voter, there are six different affiliations someone can select when registering to vote: Democratic, Republican, Green, Libertarian, None (No Affiliation) and “Other.”
If the voter selects “Other,” a blank space is provided to fill-in a party of choice. From the Pizza Party to the Squirrel Reform Party, “Other” can range to unlimited options.
Voters who register outside the Democratic or Republican parties in Pennsylvania have increased significantly over the past eight years.
Seven Pennsylvania counties — Montgomery, Westmoreland, Washington, Luzerne, Philadelphia, Bucks and Chester — saw these voter registrations increase between 2016 and 2024.
Philadelphia County stands out among the commonwealth. From 2016 to 2024, voter registrations outside of the major parties increased by 37%. In just eight years, the county went from 123,912 to 169,758 registered voters.
Bucks and Montgomery counties, both of which border Philadelphia, had a similar pattern. From 2016 to 2024, Bucks County grew by over 12,000 voters outside the major parties. The numbers surged in Montgomery County from 89,354 in 2016 to 106,939 in 2024 — a 19.7% increase.
Elections are decided by those who vote
While voter registration numbers are important, those who turnout and cast ballots determine the election.
About 89% of eligible voters are registered to vote in the commonwealth but only 76.4% of those voters cast a ballot. In 2020, 2,145,917 registered voters opted to not vote.
Philadelphia County had the lowest percentage voter turnout of all counties in Pennsylvania. In 2020, only 66% of registered voters came out to the polls on Election Day.
Centre, Erie, Luzerne and Warren counties also rank at the bottom five for voter participation. Erie — with a voting record of Obama, Trump, Biden — had 68.3% of its registered voters cast ballots in 2020.
Montgomery, Juniata, Sullivan, Elk and Chester counties rank in the top five of registered voters who turned out to vote.
Voter registration shifts up and down across different counties
Three counties — Chester, Montgomery and Northampton — saw an increase in their number of new registered voters.
In 2020, Chester County had 380,357 total registered voters, which increased to 396,280 in 2024. That’s an increase of 15,923. During the same time frame, Montgomery County increased from 609,195 registered voters to 632,919, and Northampton County grew from 227,433 registered voters to 234,555.
While Philadelphia County lost 23,010 registered voters from 2020 to 2024, other parts of the region gained 46,769 voters. Erie and Luzerne counties both saw a significant decrease in their voter registration. Erie’s registered voters decreased by 20,457, and Luzerne’s registered voters decreased by 11,082.
Northampton County’s registration has also been impacted by domestic migration. Between 2016 and 2022, according to the latest IRS data, 6,443 more people moved into the county than departed. In total, 90,483 individuals moved into the county, 26.4% of which moved from the New York metropolitan area and New Jersey.
The influx of out-of-state residents into Northampton underscores the uncertainty regarding Pennsylvania’s election outcome when it comes to how they will influence its margins.
The commonwealth’s margin
In 2016, Pennsylvania had 8,722,977 registered voters. Today, there are 9,161,978. Going into the 2016 and 2020 elections, the commonwealth’s registered voters were a majority Democrat. Those margins are shrinking. In 2016, the difference was 916,273. In 2020, the difference was 685,818. Today, the difference is 281,091.
And the number of voters outside of these two major parties has grown — from 1,204,339 in 2016 to 1,460,307 in 2024.
The News Lab at Penn State will have journalists traveling across these seesaw counties on Election Day. The team will speak with voters in polling places across these 13 counties to understand how their changing political alignments are reshaping Pennsylvania's electoral landscape.
You can follow their dispatches throughout Election Day, here, on LehighValleyNews.com.
This News Lab has drawn from multiple datasets to help paint a picture of Pennsylvania's shifting political geography: voter registration data from the Commonwealth of Pennsylvania (2016-2024); voter turnout data from the Pennsylvania Department of State’s “Report on the 2020 General Election”; county population data from the U.S. Census Bureau’s American Community Survey (2023); and migration data from the IRS (2011-2022). The News Lab has made all datasets used in our analysis available as part of our commitment to transparency in election coverage.
ABOUT THE NEWS LAB: The News Lab at Penn State facilitates partnerships between professional news organizations and student journalists — regularly collaborating on long-form and special projects. Their work is focused on critical coverage gaps across the Commonwealth of Pennsylvania with an emphasis on the issues most important to rural communities.