“The black vote switched to overwhelmingly and permanently democrat in 1936, there is no “almost” and there is no “50 years” and there is no “Kennedy” as is usually mentioned, or in this case, implied.”
Yes, the New Deal saw black voters switch from overwhelmingly Republican to overwhelmingly Democrat (starting in 1934; in 1932 most blacks still voted for Hoover and reelected black Republican Congressman Oscar Stanton DePriest to his congressional seat in Chicago’s South Side), but the black vote did not become monolithic (85%+ Democrat) until the late 1980s IIRC.
I believe Eisenhower got something in the mid-to-high 30s range (Nixon in ‘60 was the last time it was at or above 20%). The Black vote also depended upon where it was coming from, with Northern Blacks going Democrat before Southern Blacks did. Interestingly, Blacks weren’t still necessarily monolithic Democrat even during that transitional period into the early ‘60s. Such as in the 1950 Maryland Senate race, Baltimore Blacks voted overwhelmingly for Conservative Republican John Marshall Butler over liberal Democrat and racist anti-McCarthy antagonist Millard Tydings. However, the year before in a 1949 Special election in NY, Republican John Foster Dulles in the Senate race apparently received only around 1/10th of the Black vote, more what we tend to see these days.
One interesting fact I learned about the 1934 House race in IL-1 that featured the first election of a Black Democrat (Arthur Mitchell) over the Black Republican incumbent Oscar DePriest is that Blacks did NOT provide the Democrat the margin of victory. It was an almost uniform vote of Whites coupled with a minority of the Black vote in the district for Mitchell that gave him a victory (moreso when Mitchell won, he took the rather “Conservative” position that he just simply wanted to be viewed as “A” Congressman, rather than a “Black” Congressman and automatic national spokesman for the Black community as DePriest was). It was Mitchell’s refusal to act in such a role that saw him replaced by 1942 by William Dawson, who nearly beat Mitchell in 1938 as the Republican nominee. The GOP still got above 40% of the vote as late as 1946, but after the 1950s and disintegration of the Chicago GOP did the vote dwindle to virtually nothing (1956 was the last relatively decent year when Ike did well). From 1964 onwards, it came down to the level we’ve mostly seen since.
You still had another examples of Blacks providing the margin of victory in the Birmingham Mayoral election in 1967 for the Republican and other isolated or unusual incidents (the infamous Miami-Dade Mayoral when Blacks broke for the Republican Art Teele almost entirely while Cubans voted for the Democrat winner by similar uniform margins).