On May 9, 1861, the US Department of War issued General Orders, No. 19, altering the boundaries of the Department of the Ohio.
General Orders, No. 19
War Dep’t, Adjutant General’s Office
Washington, May 9, 1861
I – The Department of the Ohio is extended so as to embrace so much of Western Virginia and Pennsylvania as lies north of the Great Kanawha, north and west of the Greenbrier, thence northward to the southwest corner of Maryland, thence along the Western Maryland line to the Pennsylvania line, and thence northerly to the northeast corner of McKean county in Pennsylvania.
L. THOMAS, Adjutant General