Some information about John R. Davis (John R. Davis Building) There were two John R. Davis' (Father and Son) [See Sanderson's 20th Century History of Youngstown and Mahoning County, Ohio at pages 448-449].
He was one of the founders of the Home Savings and Loan Co.; Mahoning County's first Sheriff; a member of the Ohio General Assembly; a leading Insurance man, a member of the Youngstown Board of Education.
What was the reason for which the building that bears his name was built?
To borrow a phrase from my Dad, "don't quote me", but most likely the Buehrle Bros Home Furnishings store which provided household goods to the local community.