Coincidentally, 1994 was also the year that the percentage of the vote for Republicans was exactly the same among voters ages 18-29 and among voters 60 and older: 51 percent. In fact, until relatively recently, it was not uncommon for the voting of young and elderly Americans to look virtually identical.

Part of the reason for the Democratic swing among young people is the incredible diversity of the group. Gallup estimates that 45 percent of Americans 18-29 are nonwhite. But that doesn’t account for all of the change. As Gallup put it:

“Young adults are not more Democratic solely because they are more racially diverse. In recent years, young white adults, who previously aligned more with the Republican Party, have shifted Democratic. From 1995 to 2005, young whites consistently identified as or leaned Republican rather than Democratic, by an average of 8 points. Since 2006, whites aged 18 to 29 have shown at least a slight Democratic preference in all but one year, with an average advantage of 3 points.”