Knox’s research includes the development of high-resolution post-glacial and historical chronologies of how floods on the upper Mississippi River have responded to environmental change, and responses of river and stream systems to changes in water runoff, soil erosion, sediment mobility and storage, and human modifications of draining systems. He has published dozens of scientific papers on the results of his research. Knox’s research has been supported by the National Science Foundation and the U.S. Geological Survey. He has served on the editorial board of the Association of American Geographers since 1993.