Before the Supreme Court added the behemoth California to the list, I said homogamous marriage was spreading exponentially, in a bona fide tipping-point shape (not to be confused with the bogus tipping points all over the news). With today’s update (adding Utah and four other states), the trend is breaking the exponential curve.
(Note this chart has imitators out there, but I haven’t seen any that calculates the population percentage using the U.S. population as it changed from year to year. Note also it hardly matters.)
Note: On the term homogamy.