[N]ot every state can benefit from adding new people (nor should they). One panel featured two officials from the state of Michigan, which has suffered from a long period of decline and which continues to seek ways to right the ship. It would be possible, even easy, to resurrect Michigan. What would it take? Start with a special visa programme, in which skilled immigrants from other countries are offered easier visa terms and an expedited road to citizenship if they accept a visa that requires them to work in the Detroit area for five years. Follow that up by endowing a massive, DARPA-style energy research laboratory in the Detroit area. Set up special venture capital funds that offer excellent loan terms to start-ups connected with the lab or area universities, if they're willing to locate their new business in Michigan. Set up a special economic zone in southeastern Michigan that features an "invisible" border with Canada. Build high-speed rail lines from Detroit to Chicago and Toronto. Do all that, and I guarantee you that Detroit will be growing like mad in ten years. Honestly, even the visa programme alone might generate a turnaround.
The question is: to what end are we resurrecting Michigan? If the goal is to help the residents of Michigan, it would be much cheaper and easier to do so by investing in those individuals, in order to help them move to more successful local economies. Indeed, without investments in the people of Michigan, it's not clear how much a turnaround in the state's fortunes will benefit existing residents. Many have stayed in the state because they love the place, no doubt, but many others have not left because they're unprepared to find success in growth industries elsewhere. Moving the growth industries to their backyard won't change that fact.
If you're the governor of a declining state, you can't help but do everything you can to return your state to growth. But it's important to remember that the best thing for the American economy as a whole will often be for people to leave lagging areas.
The problem, as Burgh Diaspora notes, is not only the question of how to regenerate a community when you combine necessary investments in cultural capital with geographical mobility, but the need of how to avoid the cheap fix of avoiding population decline not by making a city more attractive for a mobile population but by keeping populations simply locked in place. Not-dismal optics can't substitute for economic development, and in the long run won't discourage emigration but simply make the system more brittle: Look at East Germany after reunification. I like the conclusion here: "[T]he main point is important. Invest in people, not places. If a place is good at developing people, then it will be a desirable residence."
For some, the climate or the built environment is more important. Both variables influence migration. However, most people will tolerate bad weather, a high cost of living, and an ugly built environment if it translates into personal or familial development. Migration is still primarily a matter of economics.
What Glaeser doesn't mention is that leaving Buffalo is more advantageous for the individual than staying, controlling for educational attainment. Increasing geographic mobility promotes economic development. Rural communities committing civic suicide understand this. Policymakers need to catch up.
This applies to human communities on all scales: cities, regions, countries, continents even. This may be easier said than done, but it has to be said.