Peterborough is a city on the Otonabee River in Ontario, Canada. According to the 2016 Census, the population of the City of Peterborough was 81,032. The population of the Peterborough Census Metropolitan Area, which includes the surrounding Townships of Selwyn, Cavan Monaghan, Otonabee-South Monaghan, and Douro-Dummer, was 121,721 in 2016. In 2016, Peterborough ranked No. 32 among the country's 35 census metropolitan areas according to the CMA in Canada. The current mayor of Peterborough is Diane Therrien.
Peterborough is known as the gateway to the Kawarthas, "cottage country", a large recreational region of the province. It is named in honour of Peter Robinson, an early Canadian politician who oversaw the first major immigration to the area. The city is the seat of Peterborough County.
Peterborough's nickname in the distant past was "The Electric City" as it was the first town in Canada to use electric streetlights.