John A. Barr was born on a farm near Akron, Indiana. He attended a one-room school and performed the usual duties required of farm boys. He worked his way through DePauw University as a part-time waiter.
Two years later, Barr transferred to Indiana University, where he studied law and worked as a waiter and as a student librarian. He graduated from law school with honors in 1930 and in 1933 joined Montgomery Ward as an attorney.
In 1935, he worked for a law firm in Gary, Indiana, and returned to Ward's legal staff in 1938. He played an important role in defending Ward during the company's highly publicized government seizure on orders of President Franklin D. Roosevelt, a seizure later declared illegal by U.S. courts. In 1949, he was named vice president and secretary. In 1955, he became chairman.