Pennsylvania’s Registration Statistics: Four Key Counties

One of the chief reasons for optimism among Trump supporters about next month’s election is the successful Republican voter registration effort in Pennsylvania. According to Seth Keshel, an election analyst on Substack, Republicans have cut Democrats’ registration lead in the state by half since 2020. They’ve improved their numbers in sixty-three of the state’s sixty-seven counties, and flipped five from a Democratic registration advantage to a Republican one.

Unfortunately for Trump, party registration tends to be a lagging indicator of voting preference, as voters in traditionally Democratic areas that swung to Trump (or traditionally Republican areas that swung away from him) update their registration to match how they were already voting. The maps below compare the 2020 presidential results by county to voter registration in 2020 and 2024, respectively. In red counties, Trump did better than voter registration would suggest; in blue counties, Biden did better (election data from Dave Leip's Atlas of U.S. Presidential Elections):

As you can see, Trump outran voter registration in rural and traditionally Democratic areas of Pennsylvania by a wide margin in 2020. In the past four years, the shift in voter registration has narrowed the gap, suggesting that most of the change in voter registration is Trump voters who were registered as Democrats or independents switching to Republican, which won’t add any votes to what he already has.

However, there are four key counties that suggest a more favorable pattern for Donald Trump and the Republicans. In three of these counties- Bucks County, in the Philadelphia suburbs, and Lancaster and Dauphin counties, in south-central Pennsylvania, Donald Trump underperformed in 2020 compared to voter registration numbers. If the shift in party registration were only caused by voters switching registration to match how they voted for president, we would expect slight gains for the Democrats. However, in all three, Republicans gained in voter registration. In the fourth, Philadelphia, Donald Trump did slightly better than voter registration would suggest, but Republican registration gains exceeded his over performance.

Bucks County is the second-most populated of the four suburban counties around Philadelphia (and fourth-most populated in the state, behind Philadelphia, Allegheny, and Montgomery). It is the whitest of the four, and has a lower average income than its blue-trending neighbors in Chester and Montgomery counties. (This is relative; the four Philadelphia collar counties are the four wealthiest in the state.) In other words, it’s the most white working-class of the Philadelphia suburbs, which has made it the only one Donald Trump has much chance of winning, or even making competitive.

There is no chance Donald Trump will carry Philadelphia, but he doesn’t have to. The Democrats need a huge margin here to offset his majorities in the rural and exurban parts of the state. Philadelphia is the most populated city and county in Pennsylvania, and the only majority minority county. If the gains Trump made between 2016 and 2020 continue, we’re likely to see it here. Whether Trump gets ten percent or twenty percent of the vote in Philadelphia could make the difference between losing or winning statewide.

Lancaster County used to be the state’s Republican stronghold, regularly voting two-to-one (or better) for the GOP. It is still Republican, but not as much as it used to be; Lancaster City is now a Democratic stronghold and Democrats have made inroads into the suburban townships around it. This trend has been largely driven by the county’s increasing diversity. Lancaster City has a large Hispanic population and is, for its size, one of the top cities for refugee resettlement in the country. If Donald Trump is gaining among minorities as much as polls suggest, this trend could start to reverse itself. The Amish (about eight percent, or 45,000 of the county’s 560,000 people) traditionally have avoided involvement in politics, but there are signs more of them are registering to vote.

While south-central Pennsylvania as a whole isn’t as Republican as it used to be, Dauphin County is the only county in the area to flip to the Democrats in a presidential election, voting for Barack Obama in 2008 and blue in each election since. Not surprisingly, it is the most urbanized and diverse county in the region; 50,000 of its 286,000 people live in the city of Harrisburg, which is one-quarter Hispanic and over forty percent black. East of the city, most of the county’s population is in rapidly Democratic-trending affluent suburbs — such as Derry Township (better known as Hershey), home both to the Hershey Chocolate empire and Penn State’s teaching hospital.

It is worth noting that all four of these counties are in south-central or southeastern Pennsylvania, where Democrats have gained since the 1990s, preventing the Republican trends in western and northern Pennsylvania from turning it into a safe red state. If the Republican registration gains represent more than just people who already voted for Trump joining the party, they could be a good sign for the party’s prospects next month.