Highway 502 begins at a junction with Highway 11 approximately east of Fort Frances. It progresses north through an isolated region dominated by the forests, exposed bedrock, rivers, numerous lakes, muskeg and mountains of the Canadian Shield, encountering no communities or significant roads along its route; it does provide access to numerous logging and mineral access roads. Highway 502 ends at a junction with Highway 594 approximately west of Dryden and west of Highway 17.
History
Historically, the Ontario Highway 502 designator has been used on two different, unrelated roads.
Before the completion of Ontario Highway 401 between Belleville and Napanee in the mid-1960s, an Ontario Highway 502 designation appeared briefly on the Belleville Road as a minorbypass road allowing Ontario Highway 2 travellers to bypass Deseronto, Ontario. Highway 2, as originally designated since the 1920s, did not follow a direct path from Napanee to Belleville. It initially followed the waterfront westward through Deseronto, Ontario. The highway would then leave this road to turn northward onto Marysville Road. Marysville Road would intersect with the Belleville Road at Marysville, Hastings County, Ontario. At this point, turning west would put this traffic onto a reasonably-direct route from Marysville to Shannonville where the road rejoined the original York Road and continued westward to Belleville. A more direct routing is possible by bypassing Deseronto entirely, following the Belleville Road from Napanee directly to Marysville and then onward to Shannonville. At the time Highway 2 was originally designated in the 1920s, Belleville Road was unpaved gravel east of Marysville and a paved path through both Deseronto and Marysville was an acceptable trade-off. This would change as traffic volumes increased in the 1950s and 1960s. By 1960, a 401 segment from Shannonville westward had been completed, as had an extension of the Kingston Bypass eastward to Gananoque and the 1000 Islands Parkway. In other highway sections yet to be bypassed, substantial traffic on the busy Montréal-Toronto corridor by necessity flooded the mostly two-lane Ontario Highway 2. While Highway 2 was left on its existing routing the Belleville Road was designated as "Highway 502" in 1956, a bypass which would miss Deseronto entirely and save a few precious miles. The completion of Highway 401 between Shannonville and Napanee in 1964 would render Highway 502 as a Highway 2 bypass superfluous, although it retained the designation until 1973. While Highway 2 would retain its original routing, the Belleville Road reverted to county jurisdiction.
Northern Ontario
In 1972, planning began for a new route between Highway 11 near Fort Frances and Highway 17 near Dryden. The existing Highway 812 extended north from Highway 11 for approximately, and so work began to extend it north the remaining. During construction, the route was referred to as the Manitou Road. It was completed in the fall of 1980 and designated Highway 502. For several years in the late 1990s and early 2000s, the highway became used by trucking traffic as an alternative to Ontario Highway 71, after load restrictions were placed on the Sioux Narrows Bridge.
