Well hasn't the term chicagoland invented to sound like the Legoland theme park in the first place? I guess if another large city name was terminating with -ney its metropolitan area would also be called in a similar way.
Etymology. Chicago + land. Generally thought to have been popularized by Robert R. McCormick, editor and publisher of the Chicago Tribune, first using it on page 1 of the July 27, 1926 issue, although it may have been coined much earlier.