Combined Statistical Areas by Area in Square Miles

[Yuri]

Urban areas and metro areas are different concepts and they both have a purpose.

Administrative divisions matter as they shape people’s lives in lots of ways. A person living in Lake County inside the UA and other outside of it don’t live dramatically different lives. That’s why metropolitan areas are vastly more used than urban areas everywhere in the world.

The smallest universal administrative unit in the US is a county and that’s why they used them as the base for their metro areas (MSA and CSA) definition. They only happen to be bigger. In France, the smallest unit is the commune and they have 16 km2 on average; in the contiguous US, counties have 2,400 km2 average. But as you showed for Chicago and I for Los Angeles, population for urban area and metro area are virtually the same.

Counties size doesn’t make US metro areas to be oversized population wise.