But that's not what the data shows. People from blue states are moving to blue cities in red states. Left leaning people are moving to similarly left leaning areas. Austin, Dallas, Houston, Miami, Atlanta, when was the last time these were Republican bastions? Look at the areas experiencing huge population growth. Texas might be red but the populations centers haven't been for years.
I think in the particular case of my co-worker the blue is spilling into the traditionally red rural areas. The population centers inevitably must expand to handle the migration.
This is a good point, but it would be intellectually disingenuous not to acknowledge that they've been drawn by the policy of the red states, specifically by housing policy that's made housing costs more reasonable than the blue states.
Not that I'm a big fan of sprawl, but it's undeniable that blue state housing policy that strictly limits both sprawl AND density has been an utter disaster for cost of living anywhere where the economy is good.
The sprawl has massive hidden costs; it's a similar situation to stadiums. The city centers end up paying for it, but not reaping the benefits in tax bases / revenue.
The housing costs - while they do have a lot do with policies that prevent massive new construction - also have a lot do with a lot of people moving and wanting to move to these places.
So, question for you: What about the blue state policies is that results in their economies being good, so that these problems exist in the first place?