John Wellborn Root Jr. (July 14, 1887 – October 24, 1963) was a significant United States architect based in Chicago.
As a young man, he graduated from Cornell University and studied architecture at Paris' École nationale supérieure des Beaux-Arts, where he became friends with John Augur Holabird, the son of another famous Chicago architect.
Root returned to the States and joined his friend on the architectural staff at Holabird & Roche in 1919.
They worked on many dazzling projects in the late 1920s and early 1930s, before the Great Depression slowed new construction.
The firm weathered the Depression and Root remained an active partner into old age.