Gates wrote 10 books and 75 academic articles, and his magnum opus was History of Public Land Law Development.

Gates' PhD thesis was the basis of his first book, The Illinois Central Railroad and Its Colonization Work (1934),[4] for which he was awarded the David A.

Aside from his research, he was a renowned professor of undergraduate courses and had 23 PhD students, many of whom became leaders in the profession as well.

After he retired in 1971, he continued writing many seminal works on the subject of land law and well into his 90s was still being honored as the foremost leader in this field.

Although his early career interests were in federal land policy in general, as he himself once said, "It soon became apparent that before a history of the Public Domain could be written, special and regional studies would have to be prepared to show the functioning of the land system in a number of fairly typical states and smaller subdivisions.