It initially consisted of the county of Northumberland, excluding the township of Monaghan South.

In 1947, South Monaghan was added to the riding, so that it consisted of the county of Northumberland.

The new riding consisted of the County of Northumberland (including the Village of Hastings), but excluding the Township of Hope, the Town of Cobourg, and the part of the Township of Hamilton lying west of the Town of Cobourg and south of the Macdonald Cartier Freeway), and the Townships of Rawdon and Sidney (but excluding the city of Belleville) in the County of Hastings.

In 1987, it was redefined to consist of the County of Northumberland and the City of Trenton.

The electoral district was abolished in 2003 when it was merged into Northumberland—Quinte West riding.