139 black Democrats are then 40% of 348 Democrats.
That sets the bounds on the analysis. It is possible.
Since everybody doesn't vote according to racial category in the census, that 13.9% group will have to do a bit more to achieve 40% of the Democrat voting strength ~ so let's say if all the black voters do is always vote 100% of the time, and the other voters only vote 40% of the time, you'd have a mere 539 total Republican and Democrat voters.
Under that constraint, the 139 black voters would actually be 27% of the total vote (clearly double their percentage of the population), and a full 100% of the Democrat vote (establishing another limit since you can't go higher than 100% except in Philadelphia and Detroit).
We know that in the case of California only 60% of registered voters vote at all. Further, we know that registered voters are less than 2/3 of the total voting age population. All blacks need to do to is vote ALL the time, every time, for Democrats, and they will be the winning margin in districts where Democrats can win and they will have influence in the Democrat party way beyond what their numbers in the population suggest they might have otherwise.
Regarding Mississippi, there you don't have very many white Democrats, so blacks can be 100% of the Democrat vote and dominate the Democrat party, but the Republicans still win ~ on the other hand, Mississippi has had a very large percentage of elected officials who are black ~ since blacks are clustered in towns where there are no other kind of voters.
What's going on here that you seem to not understand is that we have different kinds of adults ~ those who always vote, those who vote sometimes, and those who are eligibile, and might even be registered, but never vote! Overlying that structure we have people who always vote Republican, those who always vote Democrat, those who vote irregularly, and those who never vote.
Black voters AMPLIFY their effective force by always voting Democrat in areas where Democrats can win ~ with not only their black voters but their white voters, and hispanic voters, and so forth.
Where there are no Democrats, nor black voters, somebody else dominates political life.
We know Democrats are, themselves, clustered in riverine urban areas ~ as are black voters. It is relatively easy in a number of states ~ not all states as you seem to demand ~ for black voters in cities to dominate the Democrat party regarding internal affairs. In those states where the Democrat party controls the statehouse and does redistricting Democrats gerrymander to make sure they create the maximum number of Democrat districts.
So you don’t have a source that can back up your silly claim that blacks make up 40% of the democrat voters.
Blacks did not take control of the national democrat party, for example being 6.6% of California did not take the state away from the republicans, perhaps you can explain how the 1.1% of the blacks in Vermont make it a democrat state.
Try to stay focused on the only thing that I am interested in.
Wrong-blacks are not “”40% of the Democrat vote overall”” and “”Blacks are today THE DEMOCRAT PARTY itself.””