From today's NY Times. As the article notes, increased assortative mating could be one reason for rising income inequality.
Americans are increasingly pairing off by education level, according to the sociologists Christine Schwartz and Robert Mare. In an article published last year in the journal Demography, they reported that the odds of a high-school graduate marrying someone with a college degree declined by 43 percent between 1940 and the late 1970s. In our current decade, the researchers wrote, the percentage of couples who are “educationally homogamous” — that is, share the same level of schooling — reached its highest point in 40 years.
Assortative mating by income also seems to be on the rise. In a 2004 study of couples wed in the 1970s through the early 1990s, the researchers Megan Sweeney and Maria Cancian found an increasingly strong association between women’s wages before marriage and the occupational status and future earnings prospects of the men they married.