[1][2] Gallian completed his Ph.D. thesis, entitled Two-Step Centralizers in Finite p-Groups, at the University of Notre Dame in 1971 under the supervision of Karl Kronstein.

He earned media attention in 1991 when he determined the methods used by Minnesota and many other states for assigning drivers' license numbers.

[4] Between 1977 and 2022, Gallian ran forty-three Research Experience for Undergraduates (REU) programs at the University of Minnesota Duluth.

[1] In 2019 he received the MAA's Mary P. Dolciani Award for making a distinguished contribution to the mathematical education of K-16 students in the United States or Canada.

In 2011 he received the MAA's Yueh-Gin Gung and Dr. Charles Y. Hu Distinguished Service to Mathematics Award.