There are four emgerging swing states this cycle (AZ, GA, NC, and TX). But why each one is swing-y is a complicated story, involving an interlacing of demographic change with partisan shifts that differs quite a bit from state to state. 1/
One part of the story clearly is that the electorates of the four states got a lot less white over the course of last decade, with especially steep declines in Arizona and Texas. 2/ 
But out of the four, Texas is the furthest from being a battleground despite the fact that white voters make up the smallest share of the electorate among the four. There are two big reasons for that. 3/
One big factor is that the Black share of voters in Texas is only 13.2% compared to 32.2% in Georgia and 22% in North Carolina. 4/
To be sure, Latinos are a giant-sized share of the electorate in Texas (30.3%), but Latino turnout in Texas historically has been less robust than Black turnout and Latino support levels for Democrats in Texas are lower than Black support levels (65% vs 90%+). 5/
Now Latinos also are a large share of the electorate in AZ (24.3%) - and the turnout and support level dynamics in AZ are similar to TX. The Black share of the electorate also is very small in AZ (4.4%). 6/
But what makes Arizona more competitive than Texas (so competitive it almost seems in the bag for Biden) is higher levels of white support. Biden gets support from 42% of white voters in AZ vs. 31% in TX and a mere 29% in GA. 7/
Then there is the factor of people moving in from other states. In AZ & NC (the two swing-y-est of the four) half of all growth last decade came from people moving to the state, while the biggest driver of growth in TX & GA was births. 8/
That in-migration seems to have played out especially in NC where white college-educated voters perform much more like counterparts in northern states like PA and MI. (Non-college white voters in NC, by contrast, are not too different from countparts in TX & GA.) 9/
Of course, Georgia is the counter example to Texas. Like Texas, Georgia has low levels of white support for Biden (lower than Texas, in fact). But Black voters make up almost a third of the electorate, offsetting comparatively low levels of white support. 10/
One other note: Because so much of Texas’ growth over the last two decades has been from births and because net births have been overwhelmingly non-white, that will play out bigly over the next four years when Texas is projected to add 1.3 million non-white voters. 11/
