A conurbation is a region comprising a number of metropolises, cities, large towns, and other urban areas which through population growth and physical expansion, have merged to form one continuous urban or industrially developed area. In most cases, a conurbation is a polycentric urbanised area in which transportation has developed to link areas. They create a single urban labour market or travel to work area.
Patrick Geddes coined the term in his book Cities In Evolution (1915). He drew attention to the ability of the new technology at the time of electric power and motorised transport to allow cities to spread and agglomerate together, and gave as examples "Midlandton" in England, the Ruhr in Germany, Randstad in the Netherlands, and the Northeastern Seaboard in the United States.
The term as described is used in Britain whereas in the United States, each polycentric "metropolitan area" may have its own common designation such as San Francisco Bay Area or the Dallas–Fort Worth metroplex. Internationally the term "urban agglomeration" is often used to convey a similar meaning to "conurbation". A conurbation should also be contrasted with a megalopolis. In a megalopolis the urban areas are close but not physically contiguous, and the merging of labour markets has not yet developed.