I think the term white identity politics often conjures up this image of a working-class white man who maybe lost his manufacturing job and feels he’s being left behind. There’s not a lot of evidence that such a person is the typical white identifier. People high on white identity tend to be older [emphasis added] and without college degrees. Women are actually slightly more likely to identify as white than men. And white identifiers are not exclusively found among those in the working class. White identifiers have similar incomes, are no less likely to be unemployed, and are just as likely to own their own home as whites who do not have a strong sense of racial identity.She goes on to distinguish between having a positive attitude towards one's racial identity and a negative attitude towards other racial/ethnic groups (i.e. prejudice). By attacking immigrants, Trump attracts both the prejudiced and the white identity groups, the latter which dislikes the idea of being in the minority.
Why would white identity people tend to be older? One theory would be they learned the attitude at their mother's knee, and carried it forward through life, in contrast to younger people who didn't learn such feelings in youth. Might be something to that, but I prefer another theory.
My guess is that as people get older they tend to try to understand their life. When you're young, you're too busy living to have much time for navel grazing,but when you're in your 60's and beyond you've got the time, and at least in my case the motivation to make sense of things. That's one basis for my theory. The other basis is the truism that old people view the past through rose-colored glasses. The way things were when we were young seems still the natural order of things. Changes since one's youth seem "newfangled", unnatural, wrong, or at least grating. (The last popular music I really liked and listened to was the Beatles.)
Combine the two: the force of nostalgia and the drive to understand and you have a formula for white identity.
I'd note I don't remember much "white identity" back in the 1950's, at least not identity that was separate from prejudice.
Another note--it seems to me in the 1950's older people had firmer identities--they were Catholics or Methodists, union or management, Italian or Slovak. Those identities have faded now, leaving only whiteness and politics.