Kansas City's "downtown" airport code is MKC, as another poster noted upthread. This stands for Municipal airport, Kansas City. It was originally named New Richards Field in the 1920s, then re-named Municipal for the bulk of its primacy, and then again re-named after the 1970s Mayor, Charlie Wheeler. The first Richards field, near Raytown, has also been subsequently re-named after local aviator Bill Ong, patriarch of a notable KC family.
Fun fact: Mayor Wheeler is still living (I saw him in the Westport neighborhood last month), as are all five subsequent Kansas City mayors: Richard Berkley, Emanuel Cleaver, Kay Barnes, Mark Funkhouser, and Sly James.
The airport that locals all know as KCI is, as also discussed upthread, actually coded MCI for Mid-Continent International airport. MCI became the primary airport for the region in the early 1970s.