<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by 777-232LR:
No other general city pair, such as TYO/CHI/WAS/NYC etc is specified in this manner. I must respectfully say that I believe you to be mistaken. 
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I must respectfully insist otherwise. DAL (Dallas Love Field/DALLAS) and HOU (Houston Hobby Field/HOUSTON) are two that immediately come to mind.
MKC includes the airports KMKC (Kansas City Downtown), KOJC (Kansas City Executive), KJCI (Kansas City Industrial) and KMCI (Mid Continent International). Service to London may be operated from any of those gateways, pending approval from the appropriate US authorities.