Chicago O'Hare's Airport Code
There's a fascinating story behind Chicago O'Hare Airport's airport code. You might wonder, why does it contain the letter D or R, considering that the most prominent letters in O'Hare are O and H. Shouldn't the airport code look more like OHA or something like that?
Well, as history would have it, O'Hare Airport was originally known as Orchard Field Airport (it was also known as Orchard Place Airport/Douglas Field before 1945). It wasn't until 1949, that the airport was renamed O'Hare Airport in honor of a WWII pilot.
Hence, O'Hare's airport code is ORD, named after Orchard Field Airport or more precisely Orchard Place Airport/Douglas Field.