The urban areas merged with the southern part in 2000 and the northwest.
The town, formerly known as Bolton Mills, was founded in around 1822 when James Bolton helped build a flour mill for his relative George Bolton.
By 1857, Bolton was a village with a population of 700 in the Township of Albion County Peel. The suburban housing developments began near King Street, up to 15th Sideroad of Albion (now known as Bolton Heights Road).
The temperate and fertile Great Lakes-Saint Lawrence Valley in the south is part of the Eastern Great Lakes lowland forests ecoregion where the forest has now been largely replaced by agriculture, industrial and urban development.
A well-known geographic feature is Niagara Falls, part of the Niagara Escarpment.
Almost all of Ontario's 2,700 km (1,678 mi) border with the United States follows inland waterways: from the west at Lake of the Woods, eastward along the major rivers and lakes of the Great Lakes/Saint Lawrence River drainage system. Clair, the Detroit River, Lake Erie, the Niagara River, Lake Ontario and along the St.
These are the Rainy River, the Pigeon River, Lake Superior, the St. Lawrence River from Kingston, Ontario, to the Quebec boundary just east of Cornwall, Ontario.
Parts of Southwestern Ontario (generally south of a line from Sarnia-Toronto) have a moderate humid continental climate (Köppen climate classification Dfa), similar to that of the inland Mid-Atlantic states and the Great Lakes portion of the Midwestern United States.
The region has warm to hot, humid summers and cold winters.
The Saint Lawrence Seaway allows navigation to and from the Atlantic Ocean as far inland as Thunder Bay in Northwestern Ontario.