There was a huge shift from Republican to the Democratic Party during FDR and the Great Depression. Up till that time, blacks who could vote did vote solidly Republican. FDR who offered hope to all Americans. The Democratic Party became the big tent party surpassing 50% of the electorate as to whom affiliated themselves with that Party. Whites, blacks, Hispanics, all migrated to the Democratic Party under FDR. But roughly 35% of all blacks remained loyal to the Republican Party and voted for the GOP candidates through Eisenhower. No records of Hispanic voters for this period FDR thru IKE. Nixon in 1960 received 30% of the black vote.
But beginning in 1964 through today blacks have average voting 90% for the Democratic presidential candidate. McCain who received only 4% of the black vote in 2008 holds the record for the lowest percentage of black voters since 1960. The Highest percentage of the black vote received since 1960 was Nixon in 1968 at 15% and matched by Ford in 1976. But since 1960 blacks have voted for the Democratic candidate 90% of the time. So Trump had nothing to do with the Republicans losing the black vote. That began back during FDR and the great depression. Romney in 2012 received only 6% of the black vote, Trump did better than Romney getting 8%. Also note that Obama received 93% of the black vote to Hillary Clinton's 89%. Anyway one looks at it, that is an improvement among black from 2012 to 2016 for the GOP.
Also to be noted is when JFK was president the Democratic Party still made up 50% of the electorate. Today they have fallen to 30%. Most of that drop occurred during Reagan where the Democratic Party strength dropped to 35% on average. Hispanics have voted for the GOP with a high of 40% for Bush in 2004, Reagan 37% and 35% in 1984 and 1980 to a low of 21% for Bob Dole in 1996. Like blacks, Hispanics have a long history of voting for the Democratic candidate. Romney received 27% of the Hispanic vote in 2012, Trump 28% in 2016. Obama in 2012 gathered 71% of Hispanics, Clinton 66%. Once again Trump did better than Romney and Clinton 5 points worst than Obama.
Asians there is really no historical records. But in 2012 Romney received 27% of the Asian vote, Trump 28%. Obama 73% in 2012, Clinton 65% in 2016. Once again Clinton did much worst than Obama while Trump added a point to the the GOP total. Women went to Obama 55-44 over Romney, Clinton won women 54-41. Whites went to Romney 59-39 over Obama and Trump won whites 57-37 over Clinton. Romney won men 52-45, Trump won men 52-41 over Clinton. Trump did better among men of all races than women. Trump won white men 62-31 and won white women 52-43. Clinton won black women 94-4 and also black men 82-13. Clinton won Hispanic women 69-25 and Hispanic men 63-32.
Does the above make the Democratic Party the party of women and the Republican Party the party of men? Asinine I know to put it that way, but the numbers seem to show it. But I think the more important numbers are the party affiliation numbers. On average FDR through JFK the Democratic Party had approximately 50% of the electorate identifying with them to 32% identifying with the Republican Party and 18% as independents. Through LBJ, Nixon, Ford and Carter the numbers averaging were 45% Democratic Party 28% Republican Party 27% independent. During Reagan the the big shift, the numbers became 35% identifying as Democrat, 30% as Republican and 35% as independent where they pretty much remained until Obama which now the party affiliation figures are 30% Democratic Party, 26% Republican and 44% independent.
Since FDR we have seen the once big tent Democratic Party fall from 50% of the electorate down to 30% and the Democratic isn't at all a big tent anymore but more of a far left party. The Republicans, never strong and always the smaller party has fell from 32% to 26% and is now the far right party. Independents, those without a political home has increased from 18% to 44%. Both political parties has lost middle America, have and are losing us who are center, center right and center left on the political spectrum. Being in a two party system, those in the middle usually think they have no choice but to vote Republican or Democrat. But they don't like either.