Nelson studies the impact geography and the environment had on Indigenous-European contact and interaction in North America. His current dissertation project, entitled "Five Miles of Muddy Ground: Indians, Europeans, and the Chicago Portage," examines how a particular local landscape along Chicago's continental divide influenced colonial encounter from the seventeenth century through the early Republic. More broadly, Nelson specializes and teaches on early America, the Atlantic World, Environmental, Borderlands, and Indigenous history. He has published a chapter on the American West in the Routledge History of the 20th Century United States and won the 2018 prize for best graduate submission in the Michigan Historical Review for his article, "The Ecology of Travel on the Great Lakes Frontier: Native Knowledge, European Dependence, and the Environmental Specifics of Contact." He has received generous grants through Notre Dame's Institute for Studies in the Liberal Arts and the Graduate School, as well as outside fellowships through the Newberry Library, the Bentley Library, and the William Clements Library.