He held employment as a grocery clerk, foundry worker and railway worker, but finally went into the banking industry and eventually became president of the Geneva State Bank and head of the Kane Co. Bankers' Association.

[1] In 1931, Nelson was tried on charges of malfeasance for refusing to close banks even though he knew they were in poor financial condition.

[2] As auditor, Nelson succeeded BSEIU founding president William Quesse, a close friend and political backer who had died of cancer on February 16, 1927.

[4] Jerry Horan, a BSEIU organizer whose primary job was to act as Quesse's chauffeur,[5] was elected Nelson's successor on September 6, 1927.

[1] Oscar Nelson died (most probably of a heart attack) in his home in Geneva, Illinois, in 1951.