[llamaorama]

I don't think any American city will densify substantially and come to rival the old urban cores of NYC, Philly, SF, etc. The long term trend has been a reduction in density, going back decades. However I do believe will happen is that extremely low density cities will bend closer to the norm if they are growing and are economically healthy.

Basically, I think stringy, underbuilt places with a lot of population growth like Nashville and Charlotte could easily double their density from maybe 2,000 people per square mile to 4,000 or so, matching places like Dallas and Phoenix. This would come from growth in the urban core to some extent, but also housing demand leading to more suburban apartment and townhome construction and subdivisions getting designed with much smaller lots.

However the only cities with the conditions necessary to go beyond the peak suburban density of 4,000 to 5,000 ppsm are not growing fast enough or are losing people outside their cores. Chicago will continue to build upwards inside the core but its outer areas and metro is shrinking. LA has a lot of pressure to grow upwards inside its existing footprint but the region is stagnating due to a very high cost of living, and average household sizes will probably decrease as neighborhoods gentrify and counter any increase in overall population or density.