He had a younger brother, Rezin Caleb Davis (who initially apprenticed with their father, but was a Confederate soldier and later became a lawyer in Kentucky).

After learning his trade, John Davis moved to Clarksburg shortly before Virginia authorized construction of the Northwestern Turnpike.

His wife Eliza (J.J. Davis's mother) was a pioneer school teacher in Harrison County, who taught Stonewall Jackson as well as her sons and many other local children.

They later had a son, John William Davis (1873–1955), who followed his father's career and became a lawyer and congressman, although he eventually left West Virginia and was the unsuccessful Democratic presidential nominee in 1924.

As the war ended, Davis continued his legal practice in Clarksburg, and voters elected him to the West Virginia House of Delegates in 1869.

[9] When Republican Isaac H. Duval announced that he would not seek re-election from West Virginia's 1st congressional district in 1870, Davis was the Democratic nominee and won.

His elective political years over, except for stints at the Democratic National Conventions and as a presidential elector for Grover Cleveland, Davis resumed his legal practice in Clarksburg, which came in second in the 1877 contest to become West Virginia's state capital.