The generation war is the best frame for understanding the ways that the Democratic and Republican parties are diverging.
The Republicans are leaning ever more heavily on retirees, particularly the Silent Generation (born before 1945). In the middle are the Gen Xers (born between 1965 and 1980), who are slowly inching leftward, and the Baby Boomers (born between 1946 and 1964), who are slowly inching to the right.
https://www.theatlantic.com/ideas/archive/2019/05/coming-generation-war/588670/
