He grew up as a son of a truck driver in University City[3] and was a star athlete at Mercy High School.
[5][2] After graduating, he worked at McDonnell Douglas Automation Co., Numerical Control Inc., and Cleveland Pneumatic Co.[6] In 1981, he co-founded Engineered Air Systems.
In 1983, he incorporated Engineered Support Systems Inc. as a holding company for the defense contracting division, and served as its president, CEO, and chairman until 2005.
In 1990, Shanahan sold his 10-percent ownership stake[7] to an investment group called Kiel Center Partners, which built a new downtown arena in 1994.
[5] He was survived by his wife Mary Anne, his son Michael Junior, his daughters Meg and Maureen and his 13 grandchildren.