July 10, 2014
To get a sense of how people born in different years have differed, I looked at the percentages Republican or Democratic for those both in each year in the election of 2012 (the graphs show a percentage only for the majority party, and I calculated percentage Republican, assuming that 1 percent did not vote for either party). Viewed that way, the Republican percentages by birth year varied from a high of 56 percent (birth years 1964, 1965, 1966, 1968) to a low of 45 percent (birth years 1984, 1985).
Party preference doesn’t change much from birth year to birth year, usually remaining the same or changing by just 1 percent. But you do see some flexion points. Republicans predominated in 2012 among those born in birth years 1937-48 and 1955-80, Democrats among those born 1949-54 and 1981-1994. These dates tend to support Gitza-Gelman’s theory that perceived presidential performance shaped attitudes, but not entirely: those born 1937-48 turned 18 not only during the second Eisenhower presidency but in the Kennedy-Johnson years, including time when those Democratic presidents had high job approval; those born 1949-54 turned 18 mostly during Richard Nixon’s years in office, including some when he had high approval as well.
The biggest flexion point—the biggest difference between one birth year and the next—is between those born in 1954 (49 percent Republican) and those born in 1955 (53 percent Republican). That’s double any other difference between adjacent birth years. What accounts for that? I think it’s this. There was a military draft in 1972, the year those born in 1954 turned 18. There was no military draft in 1973, the year those born in 1955 turned 18.
I also note that the 2012 Republican percentage slipped below 50 percent among those born in 1949, who turned 18 in 1967, as we were ramping up to the maximum troop numbers in Vietnam.
Which is funny, as LBJ was President then, and people hadn’t yet started blaming the GOP for the war.