[bobthepanda]

The cost per mile lumps in cheap to build rural roads with urban roads, pulling down the average. It also doesn't take into account the several hundreds of billions deficit in roads investment. At today's levels of investment American roads are crumbling and are barely holding together. And that's just the federal road system. Most states also have issues funding roads. And this is before we also calculate the cost of requiring all the parking to support a roads-or-nothing environment, or health externalities from pollution and inactivity.

The reality of the situation is that if you want a city to have more than Oklahoma City levels of density, while not having congestion completely strangle the economy, you need to build rail, or at least invest in usable mass transit. A two-track subway in Manhattan can carry something upwards of 80k people very reliably within twenty feet of right of way; a highway lane only carries about 2.7K per hour.