New Ontario is a designation for the territory that lies north of the French River in the province of Ontario. While the southern portion of the province is divided into counties, the north is composed of enormous districts---an administrative unit that was basically an unorganized county for it had no cohesive government form. The territory was too vast and rendered county government unfeasible. Government services in New Ontario were initially serviced directly from the provincial capital in Toronto.

Prior to the construction of the Canadian Pacific Railway which cut across Canada from Montreal to Lake Nipissing and then north towards Sudbury and on to Fort William, the northern portion of Ontario was uninhabited except for seasonal lumber workers, native population and fur traders. With the coming of the CPR in 1882, this territory started to open up. Settlers struck out for Lake Temiskaming and beyond. Mining activity brought more people to Sudbury and area in the 1880s. The construction of the Temiskaming and Northern Ontario Railway proved to be a true development road that opened the north. Discovery of mineral deposits along that rail line in Cobalt and area created a boom around 1905 and later. The government leaders and newspapers referred to this entire territory in northeastern Ontario as New Ontario to distinguish it from older Ontario which lay in the regions from Ottawa, along the St Lawrence River, Lake Ontario, Lake Erie and north to Muskoka. As time went on, the term new Ontario gradually fell out of favour and this vast territory became known more often as northern Ontario and continues to be referred to in those terms.