https://www.atlasobscura.com/articles/here-are-the-real-boundaries-of-american-metropolises-decided-by-an-algorithm/

When we think about where we live, usually our ideas start with political boundaries—we’d say we live in a particular state, city, or town. Ask about a neighborhood, sports team loyalties, or regions not defined by borders, though, and it might get a little fuzzier. In densely settled places like the East Coast, sprawl can make it hard to draw lines around places, too. Where in New Jersey does the New York City region end and the Philadelphia region begin?