Do airports have to be kidney shaped? If we take our cue from nature and look at how our kidneys have an efficient shape for the purpose of transferring elements from one medium to another, well, airports do precisely that as well. Therefore, it would definitely help if airports were kidney shaped because the shape is an optimum pattern for accommodating flows near and through the boundary of two media with different spatial parameters. Airports deal with the transfer of elements from one travel domain to another. For example, from airports to automobiles at airport terminals. Transportation carriers with different spatial travel domains are required to interact with some sort of preservation of the elements exchanged. An efficient design is to have the domain of the carrier with the larger space needs wrapped around the domain of the carrier with fewer space needs - the whole thing being kidney shaped. Many medium and large airports are, in fact, this shape. O'Hare Airport in Chicago is a perfect example. Others are La Guardia and Newark in the New York region, San Francisco's International Airport, and Tokyo's Narita International Airport.