King's Highway 15, commonly referred to as Highway 15, is a provincially maintained highway in the Canadian province of Ontario. It currently travels north from an interchange with Highway 401 in Kingston to Highway 7 in Carleton Place, but once continued east from there into Ottawa until that section became part of Highway 7. The length of Highway 15 is. Highway 15 was one of the original highways created by the province in 1920 to establish a highway network and qualify for funding under the Canada Highways Act. The southern terminus, originally in Seeley's Bay, was moved to Highway 2 in Kingston the following year. The routing of the highway has changed several times over the years, but it continues to serve the same region of Eastern Ontario as it has since 1920.
Highway 15 was one of the original highways created by the Department of Public Highways, the early predecessor to the Ministry of Transportation of Ontario. On October 13, 1920, several dirt roads through Leeds and Grenville County and Lanark County were designated as part of the expanding provincial highway network begun a year earlier. The route began in the community of Seeley's Bay and travelled along the current routing of the highway to Smiths Falls. It then turned northwest towards Perth. At Perth, the route turned northeast towards Carleton Place and followed roughly the same alignment as Highway 7 does today. The highway passed through that town and winded towards Ottawa, entering it along Richmond Road and ending in downtown at Highway 17. The following year, the highway was extended south from Seeley's Bay into Kingston to end at Highway 2. The route was initially unnumbered, but was designated as Highway 15 during the summer of 1925. By that point, the southern terminus was at the present junction of James Street and Main Street in Barriefield, north of Fort Henry; the northern terminus was at Carling Avenue and Richmond Road. While the southern section has changed little, Highway 15 has followed several different routings through Lanark County in its history. Originally, there were no Highway 7 markers east of Perth. The existing roads were present, but under a different numbering so what was numbered Highway 15 would correspond to the following modern designations:
From Highway 2 Kingston to Smiths Falls, the road uses the current Highway 15 route
From Smiths Falls to Perth, the road followed a route which would later become Highway 43
From Perth to Carleton Place and Ottawa, the road corresponds to what is now Highway 7, ending at Highway 17
While a more direct highway route from Smiths Falls to Carleton Place was part of the Ontario highway system, it was numbered as an extension of Highway 29, the current road from Brockville to Smiths Falls. In 1961, the "Highway 7" designator was extended to the entire length of the Peterborough-Perth to Carleton Place/Ottawa highway, removing the "Highway 15" marker from any road through Perth. The '15' designation was moved to the road from Smiths Falls direct to Carleton Place, where it appeared alongside the 'Highway 29' designation. This left a short road between Smiths Falls and Perth, which would be renumbered as Highway 43. Beyond Carleton Place, Highway 29 continued north to Arnprior, while the road from Carleton Place to Ottawa was marked concurrently as both Highway 7 and 15. In 1969, a bypass of Barriefield was built, redirecting both Highway 15 and Highway 2 around the historic village. The next change took place in 1983, when Highway 29 was truncated to Smiths Falls, leaving Highway 15 as the only number on the road from Kingston - Smiths Falls - Carleton Place - Arnprior. The road from Carleton Place to Ottawa would be designated solely as Highway 7. Prior to 1998, the road's southern terminus was at Highway 2, east of downtown Kingston, while the northern terminus reached Arnprior. Today, the Carleton Place to Arnprior segment is Lanark County Road 29, which matches the route's original MTO route number.
Major intersections
Future
There are possible future plans of twinning highway 15 southerly from Carleton Place to Smiths Falls including a new bypass around Smiths Falls and merge onto the existing highway 15 south of town. No announcements have been made.