Why is Chicago O'Haire Airport ORD?

If you have every had the experience, as I had, of arguing with a ticket agent in JFK for 15 minutes that he is about to send you bags to SJO (San Jose, Costa Rica) and not SJC (San Jose, California) then you understand the benefits of knowing the 3 letter abbreviation for the airports you are traveling from/to. But how do airports get their designations and why do some of them seem to make no sense at all?

I found a great in depth article titled Airport ABCs: An Explanation of Airport Identifier Codes that explains the history of these cryptic codes.

From ABE (Allentown/Bethlehem/Easton, Pennsylvania) to ZRH (Zurich, Switzerland), airports around the world are universally known by a unique three-letter code: the “International Air Transport Association (IATA) Location Identifier” in aviation-speak. It’s obviously much easier for pilots, controllers, travel agents, frequent flyers, computers and baggage handlers to say and write ORD than the O’Hare International Airport in Chicago, Illinois—but how did this practice start, and why are some airport codes easy to understand (ABE and ZRH) while others seem to make absolutely no sense (ORD)? Well once upon a time, before the editor and publisher of the Chicago Tribune, Colonel Robert McCormick suggested a name change as tribute to pilot Lt. Cmdr. Edward “Butch” O’Hare, United States Navy, there was an airstrip well to the northwest of Chicago with a quaint, peaceful name—Orchard Field.