I don't know where you are getting the idea that people are congregating around interstate exits now other than your personal experience. Car ownership has been trending down in the US for a few years and the urban population as a percentage of total population has also been growing for a long time.
Most of the “urban” growth is in suburbs though. According to the census bureau myself and my two neighbors on a collective 70 acres of land live in an urban area. True urban core growth is mostly in a small number of places and a narrow demographic.
