2024 U.S. Presidential Election Analysis
Philadelphia, Allegheny, and Erie Counties
&Source Data:
Contents of Report:
The Commonwealth of Pennsylvania (hereafter, Pennsylvania) has an estimated population of 13,002,909 people and is the fifth most populous state in the United States according to the United States Census Bureau. It has 67 counties, with populations ranging from about 4,300 residents to over 1.5 million residents.
The top five most populous cities in Pennsylvania are:
Pennsylvania has participated in every U.S. Presidential Election since 1795 and has voted in alignment with the nationwide winner in 48 of 60 presidential elections. (Source: Statistica) It was also one of seven broadly-acknowledged “swing states” in the 2024 U.S. Presidential Election, meaning that it was considered uncertain whether the state would vote for a Republican or Democratic candidate.
In the 2024 election cycle, Pennsylvania set an all-time record for the highest amount of money spent on political advertising in a single state; a total of over $1.2 billion. (Source: AdImpact) This was 32% more than the next highest spending state, Michigan. This highlights how coveted this state is by Presidential campaigns.
In Pennsylvania, the technology used in 2024 to cast and count votes varies county-by-county. Overall:
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This report is an analysis of election results in Pennsylvania, with a focus on in three counties:
These three counties were selected based on multiple factors, including but not limited to:
In addition to Philadelphia, Allegheny, and Erie counties, our team has undertaken preliminary analysis of many other Pennsylvania counties to investigate voting patterns. This process can be challenging, as counties report their voting data individually – meaning that the formats and data structure are not standardized. Multiple members of our team have worked to verify that the data sets used in this analysis are accurate to data sets posted by state and local governments.
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Pennsylvania reports voting data returns for each race broken down by the voting type. Individual counties each report precinct level breakdowns as well. Unlike Clark County, NV, which reports voting results broken down by tabulator, Pennsylvania counties only report their data by precinct. This means:
For each of the three counties examined (Philadelphia, Allegheny, Erie), this analysis drills down into two of the three vote types:
Because Provisional Ballots make up only 0.98% of ballots cast for President in Pennsylvania, they are excluded from this analysis.
Mail-In Voting
Pennsylvania has unusual laws regarding how mail-in ballots can be cast; specifically, what counts as part of the ‘Mail-In Voting’ category is slightly different in Pennsylvania than in other states.
Across Pennsylvania, mail-in ballots can be submitted one of two ways:
This means that a portion of ballots considered to be “mail-in ballots” in Pennsylvania were submitted using a process that is roughly equivalent to Early Voting in other states. Absentee ballots, which are similar to mail-in ballots in Pennsylvania but require the applicant to provide a reason (such as disability or illness) they cannot physically access the polls, are generally grouped together with mail-in ballots.
By law in Pennsylvania, mail-in ballots cannot be counted at polling places but must instead be processed and counted in a centralized location. County officials are not allowed to open and begin counting mail-in ballots until Election Day. The processing and counting of mail-in ballots is conducted with bipartisan teams of canvassers present. (Source: Election Facts PA) Envelopes are opened and steps are taken to open and count ballots, removing those with abnormalities. Potential abnormalities may include stray markings on the envelope used to ensure the vote cannot be linked to the voter’s name or address (the ‘secrecy envelope’) as well as ballots that were mailed without a secrecy envelope at all.
Per Verified Voting, paper mail-in ballots are then tabulated at a central location using a batch-fed optical scanner.
Because of the strict procedures surrounding the counting of mail-in votes, it is a relatively secure process that would be more challenging to manipulate than electronically-tabulated vote totals. (Source: PA Government)
Issues with mail-in ballots failing to arrive on time for voters to cast them by mail and lack of clarity around required mail-in ballot paperwork resulted in some last-minute changes to voting rules in Pennsylvania, potentially resulting in an up-tick in provisional ballots.
1,928,593 mail-in ballots were cast and counted in the 2024 presidential race in Pennsylvania.
Election Day ("Polling Place")
In Pennsylvania election data, ballots that were cast in-person on Election Day are cast at “polling places” – as opposed to Mail-In Ballots, which are turned into county election offices. In official Pennsylvania election result data, Election Day votes are captured under the category “Polling Place”.
Voters are required to vote at the specific polling place where they are registered to vote. Polling place votes can be cast by:
The exact equipment used to process votes on Election Day in Pennsylvania is listed by county on the Pennsylvania government website. Votes cast on Election Day are electronically tabulated, not counted by hand. If there are grounds for a recount, each County has its own rules surrounding how that shall be handled. In most cases, this is done by using different tabulator machines than those used on election day, and in some counties a hand recount can be done; however, it isn’t always required.
4,969,749 Polling Place (Election Day) ballots were cast and counted in the presidential race in Pennsylvania, representing the majority of votes in the state.
Provisional Ballots
In Pennsylvania, a “provisional ballot” records a vote and allows the county board of elections to determine after the fact whether or not that vote can be counted. There are several circumstances in which a Pennsylvania voter may have the option of being issued a provisional ballot.
This includes, but is not limited to:
Due to issues with mail-in ballot requirements and mail-in ballots failing to arrive in time, more voters than usual may have needed to cast a provisional ballot at a polling place on Election Day.
Despite this potential increase, approximately 68,008 provisional ballots for Harris and Trump were cast and deemed by county officials to have counted in Pennsylvania for the 2024 U.S. Presidential Election – representing just 0.97% of all votes cast in Pennsylvania (or 0.98% if third-party candidates are included). Given that this represents only a fraction of Pennsylvania votes, Provisional Ballots are excluded from this analysis.
Pre-Election Lottery
In October 2024, the America Political Action Committee (America PAC) launched a tour of Pennsylvania, during which America PAC creator Elon Musk promised to give away $1 million USD daily to registered voters in swing states in exchange for their name, street address, and phone number on a petition. (Source: AP News) The language in the petition stated that its purpose was to indicate support for the right to free speech and to bear arms, the first two amendments to the U.S. Constitution.
Musk promised to pay people $100 for signing the petition, and an additional $47 for every additional referred signatory. (Source: Forbes, Newsweek) Being registered as a voter in a swing state was a requirement for signing the petition.
Ultimately, Musk’s lawyers admitted in court that the winners of the “sweepstakes” were pre-selected. (Source: CNN) With no actual element of chance, it was therefore not a lottery. Philadelphia District Attorney Larry Krasner characterized the petition’s signatories as being “scammed for their information”. (Source: PBS)
The America PAC FAQ emphasized the importance of signatories names and addresses matching, exactly, the name and address on their voter file. Failure to provide an identical name and identical address to match the signatory’s voter file would result in the potential signatory receiving notification by email of a mismatch, and an opportunity to correct the information to ensure a perfect match.
The underlying intent for collecting this information remains unclear. One potential use case for this data is the micro-targeting of swing state voters with advertisements and/or get-out-the-vote efforts. This would not explain the insistence from America PAC that names and addresses must exactly match the voter file, to the point where a correction would have to be submitted by the signatory in order to be eligible to receive funds.
Another potential use case for which name/address exactly matching a voter file would be important is for the purpose of falsely inflating voter records in order to conceal or obfuscate artificially inflated vote counts. As 2020-2024 election security breaches implicated electronic pollbooks (also known as E-Poll Books), which contain voter registration information and are used by election officials during the voting process.
Bomb Threats
Across Pennsylvania, over 30 bomb threats were sent to election offices, courthouses, and other election-related buildings, almost entirely via email accounts linked to Russian email domains. (Sources: FBI, USA Today Network) These threats, all deemed false, forced officials to move election materials and workers to other facilities. This hampered efforts to efficiently and securely conduct the election counting processes.
These types of disruptions are a particular concern for election proceedings, as having to evacuate a polling or ballot-counting location can result in election equipment (e.g. e-Poll books, ballot-marking devices, scanners/tabulators) and/or actual ballots being left unattended for extended periods on election day.
There were only a few instances in Pennsylvania on Election Day 2024 when the bomb threats resulted in court-ordered extensions of voting hours.
Machine Failures
In addition to disruptions caused by bomb threats, Pennsylvania counties reported a high volume of voting system malfunctions on Election Day, resulting in delays and other impacts on both casting and counting votes. (Sources: Politico, Cybernews, WTAJ) A large portion of the error reports concerned ballot scanner/vote tabulator machines failing to scan ballots.
In Cambria County, ballot-printing errors have since been determined to be a key factor in machine failure to scan ballots, leading to last minute reprinting of ballots. Crawford County reported at least four instances of machines failing to read memory cards. Issues with tabulating scanners occurred in multiple counties, including Delaware, Elk, Lycoming, Montgomery, Westmoreland, and York counties. (Source: All County Voting System Report, 2024)
On Election Day in Pennsylvania, the same machines that scan the ballots are frequently used to tabulate them. (Source: Pennsylvania Voting Equipment by County) Generally, when a voter submits their completed ballot for scanning, digital images of the ballot are created and stored on memory cards that are subsequently collected from machines after the election and used to tabulate official results. The scale of disruption caused by voting equipment errors varied across the affected counties, ranging from minor delays to – in the case of Cambria County – extended voting hours and the decision to duplicate ballots rather than undertake a hand recount. (Sources: NBC Philadelphia, Altoona Mirror)
Of the counties examined in this data package, only Philadelphia reported Election Day failures of their electronic voting infrastructure. These failures appear to have had minimal reported impact, as polling locations that experienced failures had additional machines functioning properly. (Source: All County Voting System Report, General Election 2024)
Malfunctioning voting equipment does not necessarily mean that these malfunctions were nefarious or intentional. However, any kind of disruption to electronic voting equipment can provide a window of opportunity for malicious actors.
J. Alex Halderman, professor of computer science and engineering at the University of Michigan and one of the foremost election security experts in the U.S., provided the following Congressional testimony in relation to Russian interference in the 2016 U.S. Presidential election:
“Both optical scanners and [direct record electronic] voting machines are computers. Under the hood, they’re not so different from your laptop or smartphone, although they tend to use much older technology—sometimes decades out of date. Fundamentally, they suffer from security weaknesses similar to those of other computer devices. I know because I’ve developed ways to attack many of them myself as part of my research into election security threats. [...]
Cybersecurity experts have studied a wide range of U.S. voting machines—including both [direct record electronic voting machines] and optical scanners—and in every single case, they’ve found severe vulnerabilities that would allow attackers to sabotage machines and to alter votes.” (bold added)
Ultimately, about 30% of counties reported machine errors. As this reporting requirement was introduced in 2023, there are no past presidential election records to compare with 2024. (Source: PBS)
A full PDF of all post-election machine error reports can be found here on the Pennsylvania government website.
“Vote-Counting Computers”
The Election Truth Alliance did not originally plan for Pennsylvania to be the second “swing state” of focus, in part due to:
However, comments made by then-President Elect Trump at a pre-inauguration rally in Washington, D.C. on January 19, 2024 – specifically, a reference made to Elon Musk’s familiarity with “vote-counting computers” and “winning Pennsylvania like in a landslide” – prompted a shift in our focus. (Source: C-SPAN, ETA YouTube)
In our initial analysis of Clark County, Nevada, robust and comprehensive election result reporting from the Clark County Election Department – including a “Cast Vote Record” down to the tabulator level – allowed the ETA to identify trends consistent with potential vote manipulation in data from tabulators that had processed over a certain number of ballots. As such, the remark about “vote-counting computers” in a different swing state seemed particularly noteworthy.
These remarks prompted us to dive into Pennsylvania election result data, including data related to specific vote types.
Philadelphia
Philadelphia County is the most heavily populated county in Pennsylvania. The largest city is Philadelphia, which is equidistant from two other metropolitan cities, New York City, New York and Baltimore, Maryland. The county is located in the Southeast corner of the state, bordering the Delaware River that separates it from New Jersey.
For elections, Philadelphia is divided into 66 wards, each of which is split into anywhere between 11 and 51 divisions – with 1,703 in all. (Source: Philadelphia City Commissioners)
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Allegheny County
The largest city in Allegheny County is Pittsburgh, with approximately 300,000 residents. (Source: United States Census Bureau) The county is also home to smaller semi-urban communities outside of Pittsburgh.
The county is located in the Southwest portion of the state, though not along the state’s border. The Allegheny River and Monongahela River converge at “the point” in Pittsburgh to form the start of the Ohio River, which in turn empties into the Mississippi River.
Erie County
Erie County is home to the city of Erie, with a population just under 95,000. (Source: United States Census Bureau) The county is between major cities Cleveland, Ohio, to the west, and Buffalo, New York, to the east, all three of which are situated along I-80.
The county is located in the Northwest corner of the state, sitting along the Southern edge of Lake Erie, and is home to Presque Isle State Park, the most visited state park in Pennsylvania. (Source: Goerie)
(Sources: data.PA.gov, PA.gov)
(Source: Pennsylvania Election Return)
In the U.S., electronic voting infrastructure is commonly used for three key components of voting:
The type of machinery used to cast and count Election Day votes varies by county.
Per Verified Voting, mail-In ballots in Pennsylvania are tabulated centrally using batch-fed opticals scanners.
This analysis is limited to votes cast for Harris and Trump at the presidential level. While there were additional Presidential candidates on the ballot, all third party candidates combined received just 0.96% of all votes cast for President in Pennsylvania. (Source: PA Election Returns)
As Provisional Ballots make up only 0.98% of ballots cast for President in Pennsylvania, they are excluded from this analysis.
Prior to 2020, there was little to no partisan difference in the U.S. between the number of Democrats versus Republicans who chose to vote by mail. This changed in 2020, when the COVID-19 pandemic resulted in a significant uptick in voting by mail to avoid in-person contact in polling stations that could allow the virus to spread. Partisan rhetoric regarding the security of mail-in voting resulted in a widened partisan divide over vote type, with only 29% of Republicans voting by mail in 2020 compared to 58% of Democrats. (Source: MIT)
This trend has lessened in severity but does persist in 2024. While not all states track or release mail-in ballot numbers by party affiliation, available data shows that 41% of early and mail-in voting was done by registered Democrats, 38% by registered Republicans, and 21% by others. (Source: Council on Foreign Affairs)
The assumption that Republicans vote more in-person on Election Day than Democrats has been factored into our analysis. Other factors for consideration include:
High voter turnout – particularly when it occurs at only some polling stations, and to the benefit of one candidate or party exclusively – can be an indicator of potential election fraud. In election forensics, turnout is considered one of the primary data points for assessing election result data for potential fraud. (Sources: Mebane and Kalinin 2009, Kobak, Shpilkin, and Pshenichnikov)
The primary focus of this report is the Presidential race. However, down-ballot races are equally susceptible to manipulation. This is more likely to occur if the manipulation can be achieved using computer technology (e.g. tampering with a vote tabulator) as opposed to manually (e.g. physically altering paper ballots). Election infrastructure such as vote-counting tabulators can be compromised remotely, and/or days or weeks in advance of an election, and/or via brief physical interaction using a USB stick or memory card. (Click here for more sources about the vulnerabilities in American voting infrastructure, including expert testimony to Congress.)
Comparing the presidential race and down-ballot races can be a helpful way to determine whether the trends seen at the Presidential level are consistent with other races or an isolated phenomenon. This approach is less likely to yield results in scenarios like Pennsylvania 2024, where at least one down-ballot race (Senator) was viewed as among the “need to win” states in order to secure control of the Senate (alongside Ohio and Montana).
While there does remain value in determining whether there are any significant differences between Presidential votes and down-ballot votes, the prominence of the Senate race in Pennsylvania means the comparison may provide less insight.
Comparison to historical voting data can be helpful for establishing a baseline for what is ‘normal’ in a given area. In Pennsylvania, there are several challenges to doing so. This includes:
As such, a clear comparison is only truly available for 2020.
There is a common misconception among the American electorate - promoted or contested at times by political parties - that the country’s elections are “secure.” Sadly, this is not necessarily the case.
On November 13, 2024, a group of election and cybersecurity experts contacted Kamala Harris urging her to initiate hand recounts of paper ballots in key swing states.
Their concern stemmed from multiple election security breaches that occurred between 2020 and 2024, involving Election Systems & Software (“ES&S”) and Dominion Voting Systems machines, in which “software for the central servers, tabulators, and highly restricted election databases” for both voting system vendors was compromised over a multi-year period. These experts say this was “the most severe election security breach publicly known”.
Per both Verified Voting and the Government of Pennsylvania, Pennsylvania uses multiple types of ES&S and Dominion voting systems. The exact equipment used varies by county, but includes ePoll Books, ballot-marking devices, hybrid ballot marking devices/tabulators, batch-fed optical scanners, and hand-fed optical scanners.
In this report, we use the term ‘vote manipulation’ to mean tampering with cast votes in such a way that votes are added, removed, or switched. When vote manipulation occurs, someone who is not the voter is directly altering vote counts. This is in comparison to ‘election interference’, which we use here to refer to efforts to change the outcome of an election, especially by illegitimate means, but without directly tampering with votes that have already been cast.
Examples of vote manipulation could include ballot-stuffing, deleting votes, or using an algorithm to switch votes. Examples of election interference could include paying people to vote, voter intimidation, or attempts by governments to influence election outcomes in another country.
According to Election Returns PA, a state government-run website, a total of 7,034,206 ballots were cast in the Pennsylvania Presidential Election. Of those cast, 6,966,350 were cast for either Trump or Harris. The categories that Pennsylvania uses for its different vote types are:
Examples of vote manipulation could include ballot-stuffing, deleting votes, or using an algorithm to switch votes. Examples of election interference could include paying people to vote, voter intimidation, or attempts by governments to influence election outcomes in another country.
We use the term “drop-off votes” to refer to the difference between the number of votes cast for a Presidential candidate versus the number of votes cast for a down-ballot candidate of the same party.
This difference can be a product of expected human voting behavior. For example, drop-off votes may be caused by voters who:
However, drop-off votes can also be caused by malicious intervention in how votes are counted or reported. Per Behrens 2023:
“...in the presence of concurrent electoral contests on election day, ballot box stuffing and vote stealing can be detected from [drop-off] irregularities that emerge if protagonists of fraud fail to interfere into multiple races to equal extents.” (emphasis added, ‘drop-off’ term used in place of author’s term for clarity)
As such, a third potential cause of drop-off votes can also be:
Once a total number of drop-off votes has been calculated, a drop-off rate can then be calculated. Drop-off rate shows the difference in votes cast for candidates of the same party as a percentage, which can allow easier comparison across elections. We calculate drop-off rates by taking the total number of drop-off votes and dividing that number by the total number of Presidential votes cast for that party.
Written out step-by-step, that means:
A negative drop-off rate can occur when the number of votes cast for down-ballot candidates exceeds the number of votes cast for President for the same party.
What Is A ‘Normal’ Drop-Off Rate?
What constitutes a ‘normal’ drop-off rate should be expected to vary somewhat by state. (For example, in one state it may be relatively common for voters to ‘split their ticket’ while in another state voters may nearly always vote ‘straight ticket’ up and down the ballot.)
In the U.S., where significant emphasis and media attention is given to the Presidency, it is ‘normal’ for the candidate for President to receive on average between 2-3% more votes than the next down-ballot race. This margin has been narrower in 2020 and 2024 than in 2000-2016. (Source: The Center for Politics.)
In this section, we highlight:
2024 Drop-Off - Swing States vs Non-Swing States
While some drop-off between the presidential and down-ballot races is expected, SMART Elections – a non-partisan group focused on election security – notes that in the 2024 U.S. Presidential Election, drop-off rates varied greatly on the Republican versus the Democratic side. Drop-off rates for the Republican side were very high, whereas the drop-off rates for the Democratic side were quite low or even negative.
They also found that drop-off rates in swing states were significantly higher compared to non-swing states.
The chart below is from SMARTelections. Their data team performed an analysis comparing the swing states with non-swing states.
Graphics & Analysis by the SMART Elections Data Team.
All rights reserved. ©2025 SMARTelections.us #SEDATA.
There is a clear disparity in the behavior of drop-off votes in swing states (including Pennsylvania) and non-swing states. The range of drop-off rates observed in non-swing states (between 1-2% drop-off) is more in line with what we would expect to see in a presidential race, with: a) slightly more people voting for President than for down-ballot races, and b) a slightly higher Republican drop-off rate compared to the Democratic drop-off rate.
There are several possible explanations for a difference in drop-off rates, including:
In this analysis, we examine:
While the difference in drop-off rates between the two candidates is similar for Mail-In Voting (1.48% vs 1.96%) , there is a distinct difference in drop-off rate between the candidates Election Day itself (0.87% vs 4.51%).
Overall, in Pennsylvania Harris received a total of 38,862 more votes than Democratic Senator Robert Casey Jr. (for a drop-off rate of 1.14%). Trump’s total was substantially higher, 144,013 more votes than Republican challenger Dave McCormick (for a drop-off rate of 4.06%).
The chart above suggests a different statewide pattern between Mail-In votes compared to Election Day votes. Votes cast by mail were in the expected range (1-2%) of drop-off rates, whereas votes cast in-person on Election Day show an unexpected disparity.
To assess how 2024 drop-off rates compared with other recent presidential elections, we compared them with drop-off rates in the 2008, 2012, 2016, and 2020 U.S Presidential elections.
Drop-off rates were sourced from historical election bulk election data from the PA Department of State. Presidential Candidates from both parties had drop off rates above 1% from 2008-2020 in all but three instances.
The contrast between drop-off rates for Harris and Trump becomes stark when each county in the state is broken out separately.
While Harris receives a positive drop-off rate in a few counties, and Trump receives a negative drop-off rate in one county, the overall trend remains.
The two charts below take the total votes for both candidates across all Pennsylvania counties and separates them into Mail-In Drop-Off Rates by County versus Election Day Drop-Off Rates by County.
When Election Day votes are isolated, Trump’s drop-off rate is drastically higher on election day, while Harris’s is drastically lower. In one county, Harris nearly reaches a -11% drop-off rate. Some of the counties with the largest difference in drop-off rates include: Greene, Cambria, Cameron, Fayette, and Armstrong.
These Mail-In drop-off rates are not highly unusual – though there are a few counties in which the difference is more pronounced.
For Election Day drop-off rates, there is a stark drop-off difference for almost all counties.
In these three counties, Harris received 1,065,943 votes to Trump’s 496,772 votes. As these counties contain major cities (including Philadelphia and Pittsburgh), this is in line with the general expectation that Democratic candidates receive more votes in urban areas. This is backed by research from Pew Research Center.
However, the drop-off votes for Harris in these three counties account for over 80% of her total drop-off votes in the state, even though she only received about 31% of her total votes in the state from those counties.
We have separated the drop-off rates for the three counties into two charts to showcase the difference between Mail-In and Election Day votes.
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Hypothesis 1: Different Voting Types = Different Voting Behavior
Hypothesis 2: Candidate Popularity Difference
Hypothesis 3: “More Republicans Just Turned Out on Election Day”
Hypothesis 4: Vote Manipulation With Specific Impacts to Presidential Candidates on Election Day
(More Votes Cast at Precinct = Votes Skewed Towards One Candidate?)
To some extent, different patterns in voting data associated with different types of voting are expected; there are differences in the populations who tend to vote using the different methods. There is a distinction, however, between “the level of difference we expect to see” between vote types versus “a dramatic, unexpected difference” in these two datasets.
The next section of this data analysis report poses the following question:
In fair elections, we expect to see normal human variation — but also a reflection of the voting patterns inherent within a community.
A scatterplot is one way to represent data visually. Scatterplots can be helpful in that they allow us to look at all of the data points at once.
The scatterplots below show election results from San Mateo, California 2024 – a non-swing state, and a county where election results align with what we would expect to see in a fair election.
America has a mostly binary (two-party) political system. This means that when we are measuring vote share, and we are showing a data point for each candidate’s vote share in a given precinct, the “mirroring” of results is visually expected.
The charts below represent Mail-In Voting data in San Mateo, California. As a Democratic-leaning area, and because Democrats are more likely to vote by mail, the fact that Harris receives around 80% of the vote share and Trump receives around 20% of the vote share is consistent with our expectations.
There are three noteworthy elements to highlight about the San Mateo 'Vote Share by Vote Count' charts.
In the San Mateo Election Day voting data above, there is a shift in voter preference reflective of what is expected based on vote type: rather than precinct vote share generally falling around 80% Democratic and 20% Republican, it is instead around 60% Democratic and 40% Republican.
The Election Day Dan Mateo data is what we would expect to see with respect to Republicans voting in higher numbers on Election Day than by mail. A pair of broadly linear data points across all precinct sizes and with normal variation, just in a different place on the chart to reflect the different vote share received on Election Day versus Mail-In data.
This is not what we see in Philadelphia, Allegheny, and Erie counties. In those counties, we observe a largely ‘normal’ pattern for Mail-In voting data – but we see distinct deviations from expected patterns in Election Day voting data.
Philadelphia is made up of 1,703 electoral units, meaning that charts for Philadelphia have many data points. It is also an overwhelmingly Democratic city, having voted for the Democratic Presidential candidate by 81.44% in 2020, 82.53% in 2016, and 85.2% in 2012. As such, the majority of precincts voting mostly Democratic is in line with expectations.
The “mirroring” is also expected, given the U.S. two-party political system (i.e. if Harris received 60% of the vote at a given precinct, Trump likely received the other 40%, plus or minus around 1% received by third-party candidates).
As in San Mateo, there is greater variation in candidate vote share in precincts where fewer votes were cast, meaning that a small number of ballots could have a large impact on vote share. This averages out over time in precincts where more votes were cast, creating the ‘broadly linear’ data points as expected.
This means that, overall, Mail-In votes look largely as expected.
The pattern that emerges on Election Day does not.
The patterns made by each candidate’s data points are clearer when isolated. While one portion of the precincts appear to remain largely linear as expected, there is another portion of precincts that appears to separate and skew in precincts where more votes were cast: a downward skew for the Democratic vote share, and an upward skew for the Republican vote share.
This ‘split’ appears to begin in precincts where a little over 200 votes were cast and counted, with some precincts shifting closer to 40% vote share for Harris and closer to 60% vote share for Trump. The separation creates a ‘claw-shape’ when represented visually, diverging – partly, but not entirely – from the expected linear representation.
This shift away from the expected Election Day voting pattern is more clearly visible and consistent in Allegheny and Erie Counties.