The tendency for an increasing number of people to live, work, and play in metropolitan areas is perhaps the most distinguishing mark of the United States in the twentieth century. In 1961 the term, "Megalopolis," was used to describe the merging of thirty-one metropolitan areas into one supermetropolis extending in an unbroken urban chain from 'Boston to Washington, D. C.1 Other areas of the country, most notably around the Great Lakes and Los Angeles, also display similar tendencies. The purpose of this paper is, first, to operationally define "megalopolis" and, then to utilize this definition in determining the extent of megalopolitan development in the Dallas and Fort Worth Standard Metropolitan Statistical Areas (SMSA's).