The Harrisburg Capitols were members of the Atlantic Coast Football League (ACFL) from 1963 to 1969. For most of their existence, they were a farm team for the Baltimore Colts. The ACFL was a minor professional football league that operated from 1962 until 1973. Many of the clubs had agreements with pro organizations to be farm teams. In 1969, after the collapse of the , the ACFL absorbed several teams from that circuit. However, with the announcement of the in 1973, the ACFL folded.

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