 From 1979 to 1983, he was Assistant Professor of Geography at the Virginia Polytechnic Institute and State University and Director of the Department of Geography Cartography Laboratory.From 1980 to 1983, he was Director of the Department of Geography Spatial Analysis Laboratory, Virginia Polytechnic Institute and State University.In 1983, he became Assistant Professor of Geography at the University of Colorado-Boulder and in 1985 switched to Associate Professor of Geography and Director of the Deasy GeoGraphics Laboratory at the Pennsylvania State University, where he worked until 1992.