[6] In 1996, Gray and David Lowery coauthored the book The Population Ecology of Interest Representation: Lobbying Communities in the American States.
The authors argue that variations in the focus and quantity of interest groups across US states affects lobbying and legislative activities, which changes the policies that are produced.
[7] Susan B. Hansen wrote that Gray and Lowery "have an ambitious purpose: to transform the focus of studies of interest group politics", using a metaphor to population ecology rather than a more traditional organizational theory approach.
[8] A book that Gray co-edited, Politics in the American States: A comparative analysis, has been printed in 11 editions.
[9] It was the recipient of the American Political Science Association's 2017 Mac Jewell Enduring Contribution Book Award, which is awarded "every three years to a political science book on the subject of U.S. state politics or policy published at least 10 years prior to the award being bestowed that stands as an enduring contribution to the literature", specifically "those classic works" which "have been crucial in setting the direction of scholarship the field since their publication.