The Concentric zone model also known as the Burgess model is one of the earliest theoretical models to explain urban social structures. It was created by sociologist Ernest Burgess in 1924.
Based on human ecology theories done by Burgess and applied on Chicago, it was the first to give the explanation of distribution of social groups within urban areas. This concentric ring model depicts urban land use in concentric rings: the Central Business District (or CBD) was in the middle of the model, and the city expanded in rings with different land uses.