His father, the son of an earlier Joseph Jenckes, operated a sawmill in Warwick, but shortly thereafter settled in Providence.

[1] The subject Joseph Jenckes became a freeman in Providence in 1681, and ten years later began an extensive career of civil service to the colony.

[1] One of the major issues concerning Rhode Island during Jenckes' terms of leadership was the boundary-line controversy with the neighboring Colony of Connecticut, and between his two terms as Deputy Governor Jenckes was in England with Richard Partridge to obtain royal intervention in this dispute.

[1] The following year he wrote a letter on behalf of the General Assembly to King George II thanking him for his protection of Rhode Island's "charter privileges".

[2] Jenckes' first wife was Martha, the daughter of John and Mary (Holmes) Brown, with whom he had nine children and at least 68 grandchildren.