After graduating the University of Minnesota Law School in 1911, Abbott McConnell Washburn---known to friends as "Mac"---joined his father's firm, Washburn, Bailey & Mitchell, in Duluth. Except for service in the Army during the World War, he was a member of that firm until 1930 when he moved to Minneapolis to take the position of General Counsel of the First National Bank. He died on September 10, 1939, at age fifty-two. In memorial services for the Hennepin County Bar Association the following year, Clark A. Fletcher recalled him:
"'Mac' Washburn was a very unusual man. His outstanding characteristic was his keen, receptive, quick mind. He could analyze a legal problem in less time than any lawyer I ever knew, quickly winnowing the grain from the chaff and finding the particular kernel in which the germ of the problem existed. When meeting him, one was impressed by the way in which he rapidly expressed his views in an explosive, staccato form peculiar to him. Through all that he said shone his kindly nature, sympathetic to the problem on which he was in contact. He was not one who 'wore his heart upon his sleeve.' He was blessed with a generous nature and a deep sense of loyalty. He gave an attentive ear to the problems of his associates, employees of the bank, and his relatives, and gave liberally of his time for their benefit. He had a large group of intimate friends among leading men of all ages in this community. He had a very wide range of acquaintances among lawyers and bankers of the state and nation and for many years prior to his death occupied an enviable standing at the bar and in banking circles."