Henry Mohnkern was a carpenter by trade. After a brief stop in Altoona, Pennsylvania, Henry settled in Venango County apply his trade. First at Rockmere, then at the furnace at Black Forge in Cranberry Township. He built the big bellows for the forge before spending two years in Butler County, and a short time in Clarion County.

He and his family settled in Siverly in 1863. As a pioneer mechanic he found plenty of work at his trade building many houses in Oil City. He appeared on the census of 1840 in Cranberry Township, Venango County, Pennsylvania.

He and Mary Ann Winger were living in Beaver Township, Clarion County, Pennsylvania, in 1850.

He was living in Waterson's Ferry, Madison Township, Clarion County, Pennsylvania, in 1860.

He was members of the Bethel Methodist Episcopal Church.

He was living in Cornplanter Township, Venango County, Pennsylvania, in 1870.

He was living in Siverly, Cornplanter Township, Venango County, Pennsylvania, in 1880 with his daughter Elizabeth Culbertson.