Those were different times

 From the New York Times:  "[Danzy] Senna, 53, was born in Boston, the daughter of a white, patrician mother . . .  and an African American father. Her parents . . .  were in the first cohort of interracial couples who could legally marry in the United States."  Hold on a minute--in 1967, the Supreme Court ruled that state laws prohibiting interracial marriage violated the Constitution, but only a minority of states (all Southern or border states) had such laws.  Some states had laws against interracial marriage until the 1950s and 1960s, and in those it would be reasonable to speak of the "first cohort" of interracial couples, but Massachusetts had repealed its prohibition on interracial marriage in 1843.  It wasn't the first in that respect--five of the thirteen original states (New York, New Jersey, Pennsylvania, Connecticut, and New Hampshire) never had laws against interracial marriage.  So although interracial marriages were rare, they've been around since the beginning of the United States.  The Times wasn't the only one to get this wrong--Senna's Wikipedia biography says that her parents "married in 1968, the year after interracial marriage became legal," and cites a Canadian Broadcast Company article, which says her parents "wed a year after interracial marriage became legal."  Why would multiple sources make this mistake?  It's not hard to find the information on differences in state laws (the Wikipedia article on interracial marriage in the United States has it.  

I would guess that it involves a change in the way of seeing racial discrimination--in the 1950s and 1960s, the prevailing view was that it was mostly a regional issue--the problem was to get the South to catch up with the rest of America.  Since that time, there has been a reaction against this view, which has sometimes overshot the mark.  You could say that we've gone from a realization that racism is present even in Boston to an assumption that Boston was and is no different from anywhere else.  

Of course, at the time her parents were married there was a lot of opposition to interracial marriage, even where it was legal.  In 1968, a Gallup poll asked "do you approve or disapprove of interracial marriage?"--20% approved and 73% disapproved.  A NORC survey asked whites "Do you think there should be laws against marriages between negroes and whites?"  53% said yes and 43% said no.  There were some regional differences, but they weren't as large as I expected--there was 53% agreement in New England and 37% in the Middle Atlantic states. So on this issue, law generally ran ahead of public opinion.   Educational differences were much bigger--about 75% of people with a grade school education and only 12% of college graduates said yes.  

[Data from the Roper Center for Public Opinion Research]