McCrossin was the son of Edward James McCrossin and his wife, Bessie, who was the widow of Florence Downey of Charleston County, South Carolina. He was sometimes called E. J. McCrossin Jr and misidentified in reports of his death as "Edward James McCrossin".
McCrossin grew up in the family's home at 3314 Cliff Road and attended Birmingham City Schools. He was enrolled as a freshman at the University of Alabama in 1915 and graduated with a degree in engineering in 1919. While in school he served as an artillery lieutenant in the U.S. Army during World War I.
McCrossin was appointed by Governor Frank Dixon to succeed William Hillhouse as Alabama's chief mine inspector in 1939. During his term he investigated fatal explosions at the Powhatan and Praco mines and other deadly incidents at Acmar and Docena.
McCrossin was president and director of the Birmingham Engineers Club. During World War II he served as state mining coordinator for the War Production Board and as chair of the Birmingham chapter of the National Committee for Conservation of Manpower in War Industries.
- "Industrial Safety Director Added To Fatalities in Sayreton Disaster." (August 30, 1943) The Birmingham News, p. 9
- Erwin McCrossin at Findagrave.com