The June 2 primary will be Pennsylvania's first run at mail-in ballots, and it appears to be the way about 2% of the state's voters are going. How do I know that? Python, a lot of coffee, and data from the @PAStateDept. Let's dive in.(1)

As of around April 25, Pennsylvania had roughly 8.5 million registered voters on its rolls. Philadelphia and Allegheny counties the first and second most voters at over 1 million and nearly 900,000 voters, respectively. (2)

Over 1.2 million registered Pennsylvanians have already requested a mail-in ballot as of about May 18. That's roughly 14% of all registered voters who have requested to cast their ballot by mail rather than going to the polls. (3)

Democrats have certainly applied for more mail in ballots than Republican voters by county. Democratic ballot applications outnumber GOP voters in some counties by tens of thousands, where as Republican-led counties only surpass Democrats by 1,700 at most (4)

That is a little surprising considering Republican voters tend to outnumber Democrats in most counties. Of course, asking for a ballot by mail isn't the same as actually casting a vote. (5)

After a voter gets their ballot, they can fill it out and send it back to their county elections board to be opened on June 2. The county average for returned ballots as of last week was about 3,700. About 20% of all ballots have been returned (6)

In order to be counted, a ballot must be received by the county no later than 8 p.m. on June 2. Which might be what Bucks County voters are waiting for. Only 84 of almost 70,000 mail in ballots have been returned (7)

So far, Bucks County mail in ballots returned makes up about 0.01% of the county's total voters (about 459,000 voters). The county average for returned ballots across the state is 3%. About 2% of all voters have cast a ballot in the June 2 primary (8)

For the most part, Republicans and Democrats are keeping up with each other in most counties where returned mail in ballots are concerned. Cast ballots for both Republicans and Democrats represent similar percentages of all voters.(9)

Speaking of primaries, no less than 25% of voters currently registered by county turned out to the polls in the 2016 primary. Voter turnout based on today's registrations climbed as high as 43% in some counties (10)

As a party comparison, more currently registered Republicans voted in the 2016 primary than did registered Democrats by county. It's a primary, so take that with a grain of salt. I just thought it was interesting. (11)

That was fun. Here's the link to Bucks County's Board of Elections for more information on voting by mail http://buckscounty.org/government/CommunityServices/BoardofElections
And MontCo
https://www.montcopa.org/753/Voter-Services

@skylar4congress pointed this out above and I wanted to make sure it was noted separately as well. Part 3 of this thread should have this image instead of the one I put up. I named my JPGs too similarly while I was doing this.