A Study of Major Impact: Assortative Mating and Earnings Inequality Among U.S. College Graduates

This research has two goals: to measure the extent of assortative (non-random) mating by college major in the United States, and to assess the extent to which assortative mating by college major increases earnings inequality among college-educated couples. Assortative mating of college graduates with other college graduates has been extensively studied, but research on assortative mating by field of study is rare. The analysis uses a large sample (659,732 couples) from five years of the American Community Survey public use files to group college degrees into nine categories, compute the frequency of all marital pairings, and compare these frequencies to a random assignment of pairings. The results show that assortative mating by college major is common for all majors and both genders, and that these results are robust to division of the sample by age group. Because high-earning majors tend to be married to spouses from the same high-earning major group, and likewise for low-earning majors, assortative mating increases earnings inequality among two-earner college-educated couples. The extent of this increased earnings inequality is calculated with both dollar measures and standard aggregate measures of inequality. Thus college-educated Americans tend to marry persons with similar college majors and this tendency measurably increases earnings inequality among college-educated couples.