The riding's borders have differed slightly since its creation in 1953, but has always included most or all of
Peterborough County and its county seat of
Peterborough, Ontario. Prior to 1952, Peterborough was split into two ridings, one of which was sometimes partly joined to neighbouring
Hastings County. Since 1999, the riding boundaries and names of the provincial and federal electoral districts have been identical. It was created in 1953 from
Peterborough West and
Hastings—Peterborough. It consisted initially of the city of Peterborough and the townships of Galway, Cavendish, Harvey, Ennismore, Smith, Douro, Otonabee, and North Monaghan. In 1966, the townships of Galway, Cavendish and Harvey were removed from the riding, and the townships of Belmont and Methuen, Dummer, Smith and Asphodel (excluding the Village of Hastings) were added. In 1976, it was redefined to consist of the part of the County of Peterborough lying south of the Townships of Burleigh and Anstruther, Chandos and Harvey, but excluding the Township of Cavan and the Village of Hastings. In 1987, the Village of Millbrook was excluded, and the Village of Hastings was added to the riding. In 2003, the Township of North Monaghan was removed from the riding. In 2013, the riding lost the Townships of Otonabee-South Monaghan, Asphodel-Norwood, and the Hiawatha First Nation, while subsequently gaining the townships of Trent Lakes and North Kawartha. The riding is a noted
bellwether normally held by a member of the governing party of the day. It has only elected an opposition MP at four general elections since its creation—in
1953,
1963,
1980, and
2021. Former MP
Dean Del Mastro, who was elected as a member of the
Conservative Party of Canada, resigned from the Conservative caucus in 2013. In 2014, Del Mastro was found guilty of falsifying his expense report in the
2008 election, failing to include $21,000 in expenses and spending more than the election spending limit. He resigned his seat on November 5, 2014. Following the
2022 Canadian federal electoral redistribution, this riding was renamed
Peterborough. With a boundary almost identical to
2003, it regained all of the city of Peterborough. Specifically, it gained
Otonabee-South Monaghan,
Asphodel-Norwood and
Hiawatha First Nation from
Northumberland—Peterborough South. Meanwhile, it lost
Trent Lakes and
North Kawartha to
Haliburton—Kawartha Lakes. == Demographics ==