Abstract
We examine how the expansion of UK higher education shaped assortative mating. Combining newly digitised data on university openings with genetic and socioeconomic information from the UK Biobank, we exploit cohort and regional variation in reductions in distance to the nearest university generated by the 20th-century university expansion. Using this reduction as an instrument for college attainment, we find that increased access to higher education significantly raised the probability of marrying a college-educated spouse and modestly increased spousal similarity in the Educational Attainment Polygenic Index, with stronger effects for women. In contrast, we detect no effect on spousal wages. Moreover, we find that the 1972 Raising of the School Leaving Age had no impact on assortative mating. Overall, the results provide causal evidence that higher-education expansion increased educational assortative mating, with implications for inequality and intergenerational transmission.