I wonder if, to some extent, older people who are single, whether through death or divorce, are more likely to move into a 55+ community. Makes some sense to me; with a couple, there's some stronger incentive to stay in your existing home.

And what would that incentive be? Andy and moved into a community where, although it is not mandated that the residents must be 55*, the median age of the residents here is 67. We made the move because we wanted to be in a place with lots of amenities that we can enjoy when we retire. We also wanted to live in a place where we could meet like-minded people.