The lesson here: America's cities are economic powerhouses.
Reddit user atrubetskoy created a map showing just how important cities are to the American economy. The map was created by taking gross metropolitan product data - the total of economic activity in a metropolitan area, and the equivalent of gross domestic product for cities - and noted that the top 23 cities have GMPs that add up to about to half of overall United States GDP.
The orange regions fall in those top 23 metro areas, and the blue region falls outside them, accounting for the other half of GDP:
