Prior to its completion, the community of Killarney relied primarily on water transport via Georgian Bay and the North Channel.

From there it travels eastward through the barren wilderness of the Canadian Shield, passing through lakes, swamps, forests, and rocks on its 67.7-kilometre long (42.1 mi) journey to Highway 69.

It circles around the northern shore of Kakakiwaganda Lake before ending at an interchange with Highway 69 midway between French River and Sudbury.

In 2010, traffic surveys conducted by the ministry at two different locations along the highway showed that on average, 500 vehicles used it daily.

[6] An ongoing series of fatal car accidents, which continued to occur even after the provincial government posted a special warning sign with flashing yellow lights on the curve, was cited by residents of the area as an important factor in favour of the northward extension of Highway 400 to Sudbury.