During the 20th century the technique of zoning became increasingly more important. Based on modernist principle that like activities should be located near one another and that manufacturing and residential functions should be separated, zoning partitioned land use according to each.

Planners and policy makers perceived a need to sort out incompatible activities, set some limits upon building size, and protect areas from being spoilt. Zoning regulations first introduced in the early decades of the 20th century were the means for achieving these goals. Main purpose of zoning was segregation of particular uses of urban space. Thus, housing, manufacturing and retail activities which formerly intermixed now took place in different parts of the city.¹