Among the obscure data sets buried on the state's data portal is a wonderfully fascinating one: the marriage and divorce rates per 1,000 for the state, from 1958 to 2009 (1962-1964 is based on incomplete data). The divorce and annulment rate beginning its rise in the mid-1960s comes as little surprise; the rise of second-wave feminism (The Feminine Mystique came out in 1963) not only made women more willing, but also able, to get out of unhappy marriages. But it didn't stop marriages, which climbed until the mid-1970s, about the time the divorce rate peaked as well; both have been in decline since.

This, as you'd expect, is in keeping with national trends (though our divorce rate is a bit lower than the nationwide rate). Betsey Stevenson and Justin Wolfers (two economists, married to each other) explain:

Early in their analysis, Stevenson and Wolfers consider two basic trends in modern marriage and divorce. First, there is the often-cited fact that the marriage rate today is "the lowest in recorded history." But less discussed, they note, is the fact that the divorce rate today — 3.6 divorces per one thousand couples per year — is at its lowest level since 1970. This rate is going down even when taking into account that there are fewer marriages. "For marriages that occurred in the 1950s through the 1970s, the figures clearly show that the probability of divorce before each anniversary rose for each successive marriage cohort," they write. "Yet for first marriages that occurred in the 1980s, the proportion that had dissolved by each anniversary was consistently lower and it is lower again for marriages that occurred in the 1990s."

While not pinpointing a single cause for the decline in the divorce rate, Stevenson and Wolfers observe that overall, the married couples of today look quite different from those of a few decades ago. For example, data from 2000 show that marriage today is less prevalent among young adults but more prevalent among older adults, and that people are waiting longer to get married. In the mid-1950s, for example, the median age of men getting married was 23. Today, it's 27. Also, people over 65 are just as likely to be married today as people between 16 and 65.

One possible interpretation: people are getting married less often, but as a result, the marriages tend to last.

Photograph: Will Folsom (CC by 2.0)