If I was to take a guess I'd assume probably something like 5-20% of people move to another state after they retire. I mean doesn't half the state of New York move to Florida on their 65th birthday? Well no.
As it turns out only about 2% of retirees even move out of state.
At least thats what I found in this article : Retirees move, but not very far
They say :
"In 2010, just 1.6 percent of retirees between age 55 and 65 moved across state lines, according to an analysis of U.S. Census Bureau data by Richard Johnson, director of retirement policy research at The Urban Institute."
If I think about all the people I know who have retired, I can only think of one couple that moved across state lines. Everyone else I know has stayed put.
My family all lives in the state I grew up in and I'd consider moving. However if I end up living in my current state for very long I will probably have developed enough roots here that I'd probably stay put.