A great deal of (negative) attention has been devoted to the segregation of land uses in newly developed suburban areas in recent decades. The critique is that the development of exclusively residential neighborhoods and the segregation of commercial activities reduces opportunities for walking, requiring increased automobile use. This is sometimes portrayed as a recent phenomenon, bought on by the widespread use of the automobile.
Some perspective is in order, however. Land use segregation is hardly a product of the latter part of the 20th century. The original cause was not the use of the automobile (though transportation was critical). Rather, the initial separation of land uses in American cities dates to the 19th century.
The pre-industrial walking city at the start of the 19th century had very limited separation of different land uses. Given that interaction was limited by reasonable walking distance, different activities just could not be located that far apart.
As the industrial city emerged in the 19th centure, this changed as enterprises sought to capture the advantages of economies of scale and was made possible by improvements in transportation within the city. First the omnibus, then the horsecar, and then electric streetcars and mass transit increased the distances people could travel to work and shop. Factories increased in size and formed increasingly large industrial areas. Larger enterprises required management by concentrations of office workers. The department store emerged to provide a previously unseen variety of goods to shoppers from throughout the urban area. The offices, department stores, and related retail formed the new central business districts, another area of largely segregated land uses.
Of course not all types of establishments saw these increases in scale in the 19th century. For grocery stores, the changes came later. But this was the start of increasing sizes of enterprises, made possible by improvements in transportation, forming areas of segregated land use.