According to Burgess the city continuously grew due to population pressures. As a result of spatial competition new activities are attracted to the centre of the city. This he described as central agglomeration. At the same time, other activities are repelled to the fringe of the city which he described as commercial decentralization. The activities which were located on the fringe were pushed further out from the city. Thus, the city continually grew outward as activities that lost out in the competition for space in the central city were relocated to peripheral areas.

In Burgess’s theory, the modern city grows up around the market. Therefore, the city would eventually take on the form of a highly concentrated central business district that would dominate the region and be the site for the highest competitive land prices, while the surrounding areas would comprise of four distinct concentric rings.