The racism index
If one accepts this approach, it's pretty straightforward to determine which of the two major candidates is supported by which race constituencies:
Overwhelmingly, voters of color prefer Clinton to Trump by a 47.4% margin. White voters, meanwhile, prefer Clinton to Trump by a -7.2% margin - which is to say, they actually prefer Trump. Graphed out, these margins just look something like this:
In theory, white voters, in solidarity with and deference to voters of color, should also support Clinton by a 47.4% margin. Instead, they oppose her by a 7.2% margin - a difference of 54.6%. For the sake of this analysis, I'm going to call that number the "racism index". Ideally, that index should fall to 0% as white people vote in unity with persons of color; at worst, it could hypothetically hit 200%, if both groups threw 100% of their support to opposing candidates.
The racism index, by income
Having established a racism index, it's pretty simple to conduct an intersectional analysis of race and income as manifest in the 2016 elections. All we have to do is apply the above methodology to particular income brackets. First, we chart out the preferences:
Then, we look at the margins:
And from here, we can easily assign each income bracket a racism index based on the difference between the margins. For instance, the racism index of the lowest income bracket is (47.2%+6.6%=53.8%), while that of the highest bracket is (36%+.8%=36.8%). Graphed out, our racism index will look something like this:
So what does this graph tell us? It's pretty straightforward: voting is less polarized between whites and people of color the higher everyone's income is. The only exception to this trend is among people making less than $25k a year, who tend to show more solidarity than people making more than $25-50k. Otherwise, the trend is direct.
Of course, income is not the same as wealth or precarity, and it's an even worse proxy for class; nevertheless, the numbers here seem to conform pretty closely to leftist intuitions about a relationship between racism and material conditions. Looking at a graph like this, I would be tempted to suspect that there's something about being poor that exacerbates racism, and something about prosperity and financial security that helps to foster political solidarity. If redistributing some of the wealth at the end of this graph could help bring down the racism in poorer income brackets, that strikes me as a win/win for anticapitalists and antiracists, even if it can't completely solve either problem.