@Amby....Blacks on a personal level are by far the most conservative people in America. Married Black couples with children in the home are more supportive of the "Republican" position issue by issue than any other demographic bloc. Black politics are essentially fascistic and tribal far more than they are "Democratic". There is little ideological connection between what a Black person tells a pollster that they believe or desire and how they actually vote. Black urban politics especially are nasty and ugly in a way that is hard to describe. My great grandfather was a particularly notorious ethnic Catholic political boss in New Jersey for several decades. FDR agreed to announce his run for President in New Jersey after a meeting with him. So one, I know what tribal identity politics is about, and two, I am making my assessment "matter of fact"-ly rather than judgmentally. Hillary is bear hugging Obama and Bernie is criticizing Obama, so Bernie is toast. I mean Black people voted repeated by overwhelming majorities to keep electing George Wallace in Alabama well into the 1980s.
@Tallyrand....My point was precisely that Blacks did not need to move to Macomb County to follow jobs to Macomb County. Wilson's theory falls apart upon close examination for other cities as well, but his basic story was jobs moved and Black people could not follow them. A Black person with a car living in Detroit is just as able to drive to Macomb or Oakland County as a white suburbanite in Oakland County could drive into downtown Detroit, which they obviously did by the hundreds of thousands. Perhaps in New York or Philadelphia or Chicago one could point to large urban Black populations dependent upon public transit systems that were not suited to cover low density suburbs, but I am skeptical that that describes much of the Black population in Detroit circa 1970.
As to your second point, I will point out that Howard Baker, Winthrop Rockefeller, "Bo" Callaway, John Tower and even Spiro Agnew ran well to the left of their Democratic opponents on race and civil rights when they scored the break through elections for Republicans in the South. Race was an issue that kept a very conservative white electorate in a party that on the national level was no longer willing to tolerate them. LBJ's chief lieutenant John Connally, who was the idealogical middle of the Texas Democratic Party, became a Republican in the 1970s. The day that JFK was shot, the Houston Chronicle had been setting a front page story for the next day about polling showing JFK & LBJ running behind Goldwater statewide. The story obviously never ran, but a possible Conservative Republican challenge for Texas's electoral votes was thought to be the story of the day in 1963.
The dismantling of the seniority system in Congress, which had allowed long serving Southern Democrats to dominate the institutional levers of power through the combined results of the 1920 and 1930 elections, and the Baker vs. Carr Supreme Court ruling that forced political reform onto the South at the local level that may well have been more significant than the Voting Rights Act caused enormous political dislocations in the South. In my home state of Texas and in many Southern states, Democrats switched the major offices from two year terms to four year terms offset from Presidential elections because association with the national Democratic Party essentially doomed Democrats down ballot. Democrats held onto the legislature in Texas until 2002. They lost Georgia the same year. The idea of a Nixon Southern Strategy dog-whistling on race is largely overblown. I cannot speak to the deep dynamics outside of Texas, but in Texas, the Republican party grew up in the suburbs as Midwesterners migrated in. My understanding is that the dynamics in Georgia were similar. The Congressional district I grew up in was won by Papa Bush in 1966. A demographically similar district taking in the North Dallas suburbs went Republican in the same election. Add in a somewhat eccentric guy from the wilds of West Texas and that was the Republican Congressional delegation from Texas after the 1966 election.
As for the rest of the flip, Senator Thomas Eagleton (he of electro shock therapy) predicted that "amnesty, abortion and acid" would drive the ethnic Catholics base out of the Democratic party, which it largely did. The repudiation of Hubert Humphrey and the near purging of the Democratic Party in the decade after 1968 drove huge voting bloc over to the Republicans. Jerry Falwell, Richard John Neuhaus, Condi Rice and Jeane Kirkpatrick were all Democrats in good standing until the final death spasms of the Carter administration.