When Washington’s rapid transit system was being planned, regional leaders specifically shied away from calling it a subway, primarily because much of the network would not be below ground. Of course, even in cities where terms like “subway” and “elevated” are used, trains are not exclusively above or below ground.
The graphs below compare America’s heavy rail system based on their relationship to the ground: how much they’re on it, under it, or above it. The first chart shows the total system mileage in each category, while the second chart shows the percentage of the system in each category.
If any system deserves the moniker "subway" it's Los Angeles, where everything except for the rail yard is underground. New York's famous subway is only 56% underground. And Chicago's L (for 'elevated') has nothing on Miami, with its high water table. Miami has no underground sections, and only a few places where it runs at grade. Miami is 95% elevated, while Chicago's L is only elevated 54% of the time.
In addition to the aboveground/underground descriptors, all-capital acronyms caught on briefly. As did 'metros,' which can be found from Washington to Los Angeles and Miami to Baltimore, along with in places around the globe.