The “Trump effect” on teenage politics is usually told as a story about boys and girls. Follow half a million high school seniors across five decades and a second fault line appears: whose parents went to college. After 2016, daughters of graduates surged left, sons of non-graduates swung right — and the class realignment reshaping adult politics turns out to start before anyone can vote.
Since 1976, Monitoring the Future has asked graduating seniors which party they lean toward. For the survey’s first four decades the sexes moved roughly together: both drifted Republican in the Reagan years, both drifted back. In 1976, girls leaned Democratic by 11 points and boys by 8 — a 3-point gap. The lines begin to separate in the mid-2000s and then, after 2016, tear apart. By 2024, girls lean Democratic by 7 points while boys lean Republican by 15 — a 22-point chasm between classmates who share hallways, homerooms, and a birth year.
Adult American politics has spent a decade reorganizing around education: graduates toward the Democrats, non-graduates toward the GOP. Seniors don’t have degrees yet, but they have parents. Classify each student by whether either parent finished college, and the gender divergence splits into four distinct trajectories. Daughters of graduates are the engine of the leftward movement. Sons of non-graduates are the engine of the rightward one. The other two groups moved far less. Compare the eras directly: between 2012–15 and 2021–24, college-parent girls moved 14 points toward the Democrats (−4 → +10) while no-college boys moved 12 points toward the Republicans (+1 → −11). College-parent boys added 8 points to an existing Republican lean; no-college girls barely moved (+9 → +10).
The slope chart below compresses the change into two snapshots: the last full pre-Trump window (2012–15) against the most recent four survey years (2021–24). What look like parallel cultural trends are anything but. The two extremes of the new alignment — college-parent girls and no-college boys — began the decade five points apart and ended it 21 points apart. Ideology shows the same rotation: liberal identification among college-parent girls rose from 22% to 34%, while among no-college boys it fell from 16% to 11%.
Drill into girls specifically, by mother’s education. The education gradient in liberalism is not new — daughters of college-graduate mothers were already the most liberal group in the 1980s (25% vs 16–17% for high-school-or-less). What changed is the spread. The gap between the top and bottom of the maternal-education ladder was about 8 points in the 1980s, 7 in the 2000s, and 12 points in the 2020s — with every rung rising but the top rung rising fastest. Political scientists call this sorting; a sociologist might just note that the seminar room and the break room now raise measurably different teenagers.
One caution keeps the story honest: the fastest-growing ideological label among seniors is no label at all. Almost half of 2024 seniors — girls and boys alike — say “none” or “don’t know” when asked to place themselves, up from roughly a quarter in 1976. The polarization documented here is real, but it is polarization among the engaged; the largest single bloc of American seventeen-year-olds is still politically unclaimed.