I think Americans well understand huge metro areas. Take Chicago for example: the city proper is only about 220 sq mi (~3mil people) but the metro area is around 10,000 sq mi (~9mil people). Most of that is contiguous urbanization, too. You could drive from Milwaukee, WI to Gary, IN and just about feel like you've never left a city.

Pretty much all the major cities in the U.S. are like this.

We know how to do sprawl.