Which parts of the country had the most Dewey 48 Stevenson 52 voters? The only place where I could really find a major swing was around Philadelphia.
I think those counties swung because of Philly suburbanization (since Philadelphia had more Democrats than Republicans, the new voters in Bucks Co. or something were more Democrats than Republicans) and not necessarily because of Dewey-Stevenson voters.
Stevenson did win Philadelphia by a significantly larger margin than Truman had in 1948. Truman only won Philadelphia by about 7,000 votes (or less than 1%) that year-it was the last time that Philadelphia was even remotely competitive. Truman's weakness in Philadelphia, and Dewey's dominance of the Collar Counties, is why Dewey was able to win the state by a comfortable 4% margin that year. Four years later, Stevenson won Philadelphia by 160,000 votes and 17%, although Eisenhower won Pennsylvania by more than Dewey (holding Dewey's support in the Collar Counties and improving upon him in the remainder of the state).
There were probably a good number of Dewey-Stevenson voters, given that Philadelphia's Republican machine finally collapsed in the early 1950s, and black voters were continuing their realignment between the parties. But you're also correct that turnout played a role, as Philadelphia cast about 63,000 more votes in 1952 than 1948. So the Dewey-Stevenson swing in Philadelphia was a combination of two factors, turnout and the long-term Democratic trend.
I was talking about the suburban counties, which shifted a bit towards Stevenson; I hadn't checked Philadelphia proper. But yes, Philadelphia County must have had many Dewey-Stevenson voters, given its swing.
By the way, the Republican machine may have collapsed in Philadelphia in the 1950s, but lived much longer in surrounding places. I mean, the city of Chester, the largest in Delaware County, is almost three quarters Black and had last a Republican mayor between 1996-2012, which is incredible.
Although Republican dominance in local politics there now seems really dead*, given that apparently Democrats have conquered all row offices in both Delco and Chestco, all county councillors in Delco, and the majority of them (2 out of 3) in Chestco. All things that happened for the first time since the Civil War or ever.
Maybe they will come back in the next decade. In the meantime let me say that, moving westwards, I'm waiting for Lengeschder Kaundi to fall.
* maybe the Philadelphia Enquirer, if it has not already done it, could run an "obituary" like the LA Times did with
Orange County.
