The article specifically mentions Boston, San Francisco, Washington and New York as other skyscraper cities. I think their "definition" of skyscraper city is a more about density than just the number of 40+ story buildings.
I think possibly the only legit "skyscraper city" that has been left out according to the article's "definition" would be Philadelphia which is affordable still.
This is very astute, I was using the term "skyscraper city" primarily as colorful contrast with low-density Sunbelt cities.
Philadelphia is indeed the other contender! They weirdly haven't seen explosive job growth though, despite being an excellent city. They also don't have innovative land use policy. But the vast, partially abandoned north Philly is a "reserve army of underemployed land" keeping a check on prices--as is the excellent, fully electrified suburban regional rail network inherited from the Pennsy. Maintains a wide swathe of commutable land w/in 45 mins of CBD.
Wikipedia doesn't show anything in Washington, DC, higher than 15 stories, for what that's worth. I certainly have never thought of it as a "skyscraper city".
The urban area of DC is much larger than literal Washington DC and many places there that are technically suburbs certainly do have skyscrapers. For example, "Crystal City", which is technically in Virginia but functionally part of DC.
Washington D.C. has a height limit for buildings[1]. I think the article was just mentioning it as an example of an expensive city, not trying to call it a skyscraper city.
I think possibly the only legit "skyscraper city" that has been left out according to the article's "definition" would be Philadelphia which is affordable still.