I hope that his own definition will be heeded; for the term is so awe-inspiring, and the phenomenon it describes so dramatic and novel, that it is very easy for misconceptions to take root. (Hecksher, 1964, p. vii) August Hecksher is a name that is not necessarily instantly recognizable as being pivotal to the intellectual development of research on megaregions. Yet his words offer a profound insight into what lies at the heart of a critical research agenda for those of us whose interest in megaregions has brought us to contribute to this edited collection. When you consider the term Hecksher is alluding to is ‘megalopolis’, and that his quote appears in the foreword to the paperback edition of Jean Gottmann’s classic 20th-century urban geography and planning text Megalopolis: The Urbanized Northeastern Seaboard of the United States, the relevance to contemporary work on megaregions starts to become clearer. His words take on added significance when you cast your eye over just some of the many terms that have been used over the last half century by geographers and planners to describe the phenomena of sprawling urbanized landscapes comprising clustered networks of cities: megalopolis . . . archipelago economy, galactic city, string city, limitless city, endless city, liquid city, global city-region, world city-region, mega-city region, polycentric metropolis, new megalopolis, megapolitan region, metro region, polynuclear urban region, super urban area, super region . . . megaregion.