not sure how to do this but for the history of Drum & Bugle Corps I have some info for you. It comes in part by "Piopneer Drum & Bugle Corps" Wiki page and from personal knowledge of back when I was in the Rogal Emperors Drum & Bugle Corps back in the 60s. below is some help for you.
In 1978, the Pioneer drum & bugle corps of Milwaukee, Wisconsin were one of the founding members of Drum Corps Midwest (DCM) which was the premier regional circuit in North America for over a quarter century.
DCM ceased operations in 2005, with the most prominent corps had abandoning by then, there were no other competitors. Most Corps went to DCI and the big shows.