New Yorkers who don't live in New York City hate the Big Apple.  Missourians outside of St. Louis and Kansas City are skeptical about the people (and politicians) who come from the two biggest cities in the state. Politicians from the Chicago area (and inner suburbs) often meet skepticism when campaigning in downstate Illinois. You get the idea.  People who don't live in the big cities tend to resent those who do.

Fair enough. Growing up in semi-rural southeastern Connecticut, I always hated Hartford. (Not really.) But, this map built by Reddit user Alexandr Trubetskoy shows  -- in stark terms -- how much of the country's economic activity (as measured by the gross domestic product) is focused in a remarkably small number of major cities.

In a 2011 analysis by the Brookings Institution, the think tank put hard data to just how critical big cities are to the state -- and national -- economy. Wrote Alan Berube and Carey Anne Nadeau:

In 15 states, one large metropolitan area alone accounts for the bulk of economic output. These states are located in every region of the country, from Massachusetts (Boston) and New York (New York) in the Northeast, to Georgia (Atlanta) in the South, to Illinois (Chicago) and Minnesota (Minneapolis-St. Paul) in the Midwest, to Colorado (Denver) and Washington (Seattle) in the West. In a further 16 states, just two metropolitan areas generate the majority of GDP, including California (Los Angeles and San Francisco), Michigan (Detroit and Grand Rapids), Oklahoma (Oklahoma City and Tulsa), and Texas (Dallas and Houston).

Consider that. In 31 states, one or two metro areas account for the vast majority of economic output in the state.  Those numbers make clear that while you may like to hate on big cities, you -- and we -- need them.