Minneapolis’ population recently reached 400,000 for the first time since the mid-1970’s. That’s not a surprise if you’re a Minneapolis resident, because it’s hard to miss the building boom going on in some parts of the city, like downtown and along the Hiawatha light rail line. The city government’s goal is to increase the population to 500,000, which it reached for a few years at its peak around 1950. Minneapolis has a infrastructure designed to handle a larger population, but costs are being spread among fewer people. So a larger population spreads the costs out more. Being a political person, I can’t help doing some math and noticing that getting to half a million might mean another one and a half State Senate districts, or three State house districts, either measure meaning more representation in the legislature. Obviously that depends on how long it takes to reach that figure, and what growth happens in the state overall, but in general, more people means more political clout.
Unsurprisingly, our twin St. Paul has followed the same trend of decades of population decline followed by stabilization and recent gains. It tends to be a few years behind Minneapolis at any given point, but essentially it’s having the same trend, and appears set for a building boom along the Central Corridor light rail line.
There are some problems though with raising the population further. The Star Tribune article linked above mentions that average household size has shrunk, and Minneapolis actually has more households than in 1970, when it had 30,000 more people.
There’s a physical impediment to getting back to 1950 levels, which generally goes unremarked. That over-500,000 peak was reached before construction of the freeways. The trenches weren’t there. They were dug through the parts of the city unlucky enough to get picked as routes for 35W and 94. That the freeways reduced urban populations by facilitating white flight, by making it possible to work downtown and live in the metro fringes, is pretty well known, but less considered is the direct removal of housing. Check out this photo of a bit of 35W, and the residential blocks alongside:
Figure that 35W and 94 took out a space the width city block through the entirety of their routes, and that’s a lot of lost space. That’s why I don’t believe Minneapolis can get back to a pre-freeway population without replacing the space lost to the freeways.
Of course, taking out the freeways has all sorts of problems, so that won’t happen. But it doesn’t need to. There’s an alternative, one that sounded cockamamie when I first saw it suggested, but then quickly made some sense. Put a roof on the freeways.
It’s not obvious from a map or satellite photo, and certainly isn’t obvious to anyone who doesn’t drive them, but the freeways are in trenches. Whatever the reasons for building them that way in the first place, I’m guessing one reason was so overpasses connecting city streets would be at street level. That means a roof is more practical than might be at first apparent. The effect of covering the freeways would be the same as if they were built as tunnels in the first place.
Assuming a roof were built strong enough to hold single family houses, what’s now freeway would look like any other residential streets, and there’s the additional space the city needs to its goal. With the roof to block noise, the sound barriers could come down along the frontage streets. Even if the roof wouldn’t hold buildings, the sound reduction still happens, the many side streets that were cut off 60 years ago could be reconnected. That most mostly result in convenience for residents of adjoining neighborhoods who would have an easier time getting over the freeway, but should make some reduction in traffic in the connecting streets that now have to carry everyone moving from one side to the other. A non-residential roof could still be additional green space, like a large version of the portion of Minnehaha Park that’s on top of the Hiawatha Av. tunnel. A green roof might even hold enough rain to reduce the flooding that happens in the freeway trenches during thunderstorms.
I’m not a traffic engineer, so I feel safe assuming I’m glossing over some serious problems and overemphasizing easy ones. I can’t estimate the costs involved, beyond pointing out that part one of building tunnels through the city, digging massive miles-long trenches, has already been done. So it’s just the roof part that remains, which, yes, presumably, is a massive building project, maybe on the scale of constructing the freeways in the first place.
I am sure though that if we really want to get back to half a million people, just increased density isn’t going to do it. We’re going to need more space. So unless we want to build on the parks Minneapolitans value so highly (parks are sacrosanct here, an attitude I share), roofing the freeways is the only place to find space.