Know your boundaries: reducing spatial uncertainty in urban population estimates

Deborah L. Balk, Baruch College, City University of New York (CUNY)
Thomas Buettner, United Nations
Valentina Mara, Columbia University
Donghwan Kim, Stony Brook University, State University of New York (SUNY)

Future population growth will take place predominantly in urban areas, mostly in the cities of Asia and Africa and in smaller and medium-size cities. Despite acknowledgment of the the major demographic shortcomings of urban population estimates and projections, the lack of spatial information has not yet been recognized as a fundamental omission from the record, and one that is of obvious importance to planners and policymakers. Spatial boundary information is omitted from estimates that are reported by national statistical offices, and therefore are not accounted for by the UN's Population Division in its estimates and projections of urban population. Using the UN urban population estimates as the baseline, this paper compares them with those derived from the spatially explicit Global Rural Urban Mapping Project (GRUMP). We further compare these estimates with administrative units. Implications for urban estimation is discussed. We conclude with recommendation for future data collection and methodological development.