It used to be more common for a husband to have more education than his wife in America. But now, for the first time since Pew Research has tracked this trend over the past 50 years, the share of couples in which the wife is the one “marrying down” educationally is higher than those in which the husband has more education.

Among married women in 2012, 21% had spouses who were less educated than they were—a threefold increase from 1960, according to a new Pew Research Center analysis of Census data.

The share of couples where the husband’s education exceeds his wife’s increased steadily from 1960 to 1990, but has fallen since then to 20% in 2012.

The trend toward wives being more educated than their husbands is even more prevalent among newlyweds, partly because younger women have surpassed men in higher education in the past two decades. In 2012, 27% of newlywed women married a spouse whose education level was lower than theirs. By contrast, only 15% of newlywed men married a spouse with less education. Among college educated newlyweds (including those with postgraduate and advanced degrees), nearly four-in-ten women (39%) married a spouse without a college degree, but only 26% of men did so.

Another important trend has to do with marriages between spouses with similar education levels. Even though college graduates are increasingly more likely to marry each other, the overall share of couples of similar education levels is down from nearly 80% in 1960 to about 60% in 2012.

The primary reason for the decline in the share of married couples with similar education levels is that marriages between spouses with high school or less than high school education are much less common these days — the share is down from 74% of all marriages in 1960 to 24% in 2012. In addition, adults with high school or less education are much less likely to marry. The marriage rate among this group plummeted —from 72% in 1960 to 46% in 2012.

Just the opposite has occurred among college graduates. The share of couples in which both spouses have a college degree has risen steadily in recent decades. In 1960, only 3% of couples were in this group, the share rose to 22% in 2012. Marriages between spouses with some college education were on the rise until 2000 (from 3% to 12%), but have leveled off since then.

Despite the rise of marriages between spouses with college degrees, only 22% of all newlyweds in 2012 were in this type of marriage. Another 19% were between spouses with a high school diploma or less. The share was 16% for newlyweds with some college education (but no bachelor’s degree).

Does marrying someone with less education mean “marrying down” economically? Not necessarily. When we look at the newlywed women who married someone with less education, we find that a majority of these women actually “married up.” In 2012, only 39% of newlywed women who married a spouse with less education out-earned their husband, and a majority of them (58%) made less than their husband.