The UN defines an urban area, or urban center, as a contiguous built-up area with population densities >= 1,500 pp/km^2, while the US Census Bureau defines a contiguous urban area with a population density threshold of just 193 pp/km^2 (or 500 pp/sq. mi.). Alot of American low-density suburban or exurban development would in other countries count as verging on semi-rural/countryside, and definitively would not be considered urban in most countries (e.g. US Census Bureau's urban density threshold would merge much of Southern and Central England, or the entire Tokyo-Nagoya-Osaka corridor of Japan, as one single urban area, which is silly).
Instead, I have ranked and mapped 6 of the largest US urban areas with populations > 4 million based on the UN threshold, with data and maps collected from the UN GHSL Database website:
https://human-settlement.emergency.copernicus.eu/ucdb2024visual.php
All cities are shown at the same 50 km scale.
The next 4 largest cities after are:
7. Washington DC - 3.471 million people (2,669 pp/km^2)
8. Phoenix - 2.608 million people (2,001 pp/km^2)
9. Dallas - 2.577 million people (2,084 pp/km^2)
10. Denver - 2.425 million people (2,031 pp/km^2)
Ultimately the density standard seems to work very well for the most part, but there are strange distortions due to how strict the definition is with small gaps in development (which is why Dallas is chopped up into 4-5 different pieces, or Phoenix split into two by a wide river, making them seem smaller than they otherwise are).
Additionally, the UN definition of urban areas favors western sunbelt cities and South Florida where medium-density development patterns are more consistent deep into suburbs, and disfavors southern and eastern cities where urban development peters out into very low density suburbs, which is why you get unexpected results like Miami having more people than Chicago, or NYC and LA coming in neck and neck in population.
Linear Mode
