Spatial mismatch was first proposed by John F. Kain in a seminal 1968 article, "Housing Segregation, Negro Employment, and Metropolitan Decentralization". That article did not specifically use the term "spatial mismatch", and Kain disclaimed credit. In 1987, William Julius Wilson was an important exponent, elaborating the role of economic restructuring, as well as the departure of the black middle-class, in the development of a ghetto underclass in the United States.