See the U.S. flatlining in transit miles per capita
A devil’s advocate would rightfully argue that that’s expected given the much lower average population density of the US -- the same factor that made it a struggle to get broadband Internet to everyone in the US. Bizarre to use a nationwide per capita as a basis for mass transit comparisons. It should be a city-by-city comparison that groups cities by comparable population density. US cities would likely still come out behind and embarrassed, but more accurately so.
Consider the marketing angle -- instead of saying “the US is losing” (which diffuses responsibility and makes plenty of room for finger-pointing), instead say “@[email protected]’s city lost its ass in the bi-annual city infra competency competition”. Then that mayor has some direct embarrassment to pressure action.
Id be curious the surface area of those million population centers? Lots of the US is very spread out even for "cities" only the old cities on the East Coast have significant density.
Zoning to prohibit people from living on 99% of the land so that the population is dense enough to fully benefit from public transit? Lots of states don't even have a true city at all. Should those be zoned as national parks?
Edit: I think I missed the point. You're talking about just city zoning. Still, not a magical fix and would likely require moving lots of people and demolishing/building buildings and infrastructure. However, it's more realistic than zoming everyone out of the midwest.
The nationwide fuckup in the US is zoning rules that block commercial venues from residential regions, which means people cannot step outside their front door and get groceries in a 1 block walk. People are forced to travel unwalkable distances to reach anything, like food and employment. Which puts everyone in a car. Which means huge amounts of space is needed for wide roads and extensive car parking, generally big asphalt lots, which exacerbates the problem because even more space is wasted which requires everything to be spread out even more, putting resources out of the reach of cyclists. Making the city mostly concrete and asphalt also means water draining problems where less of it makes it into the soil and groundwater, and it means the city temp is higher because of less evaporative cooling from the land mass (Arizona in particular).
This foolishness is all done for pleasant window views, so everyone can have a view of neighbors gardens instead of a shop front.
Europe demonstrates smarter zoning, where you often have a shop on the ground level and housing above it. You don’t need a car because everything is in walking or cycling distance. But you more likely have an unpleasant view.
Subways are pretty much exclusively built in the cities
Not just any city. Dense cities. Cities that are so densely populated that it would be /impossible/ for every person to move around in a car. Countless US cities are not even close to crossing that threshold. It just makes no sense to look at nationwide per capita on this. Only a city by city comparison of like with like population density is sensible.
(edit)
There is a baby elephant in the room that needs mention: US cities are designed with shitty zoning plans. They are designed so that each person on avg needs to travel more distance per commute to accomplish the same tasks (work and groceries). This heightens the congestion per capita. So ideally we would calculate daily net commute distance needed per capita plotted against subway track per capita for cities of comparable people per m². Which would embarrass US city mayors even more.
At a time when we also need more housing density, I feel like subways go hand-in-hand. And even for shittily zoned cities with huge suburb-like areas, I feel like most would benefit from at least nearby subways with parking lots (or ideally, additional bike paths).
By size, you are referring more specifically to area. Area while neglecting population is inversely proportional to population density¹. But even apart from that -- how does that support the claim that it’s sensible to disregard cities and just look per capita nationwide? NYC should be compared as a single whole city against other cities of comparable population density. Area does not matter as an independent variable on its own. What would the point be to blur NYC into a nationwide track per capita?
BTW, NYC has a subway system. I’ve used it a few times and it was not even close to being overcrowded but maybe I had lucky timing. Are you saying more track is needed there?