File:Map of the North Simcoe Railway, and its connections.jpg

English: This map of southern Ontario shows the route of the mainline and planned expansions of the Northern Railway of Canada.

The mainline is in black and also indicates the main stations on the route. The original route ran from Toronto to Barrie at Allendale Junction and then turned west and northwest for Collingwood. The second branch, labelled "Muskoka Branch", was the "Toronto, Simcoe and Muskoka Junction Railway" expansion from 1869. At the end of the line in Collingwood, a white outline shows the route to Meaford, labelled "North Grey Branch" on this map, but officially known as the "North Grey Railway". Similar unlabelled light outlines at the end in Gravenhurst shows the planned northern expansion as the "Northern and Pacific Junction Railway", which ultimately ran to North Bay.

The lines in red are the main focus of this particular map. Competing with the Hamilton & North Western (H&NW, thin black line just to the left of the red ones) led the Northern to propose several new routes to open up other markets in Simcoe County. The "North Simcoe Railway" would split off just north of Allendale and connect to the port town of Penatanguishene. The "South Simcoe Junction Railway", labelled "South Extension of North Simcoe", would compete with the H&NW through southern Simcoe County. Ultimately the H&NW won the contest and funds were raised by Simcoe to help pay for its construction. The Northern abandoned the South Simcoe section and moved the terminus of the North Simcoe to a point some distance west, closer to Angus, not far from the point where the South Simcoe crosses the mainline on this map.

Southern sections between Allendale and Toronto remain in use as GO Transit's Barrie line. The section from Allendale to Collingwood is officially in use, but the rails are heavily overgrown. The rest of the routes in the southern Ontario area have been turned over to rail trail use, especially the North Grey, now a major tourist pathway. The section from Allendale to Gravenhurst is largely unused, while north of there it forms the CN mainline, connecting to an extension of the Ontario Northland Railway at Gravenhurst.

The map shows many other routes and expansions as well. Of note is the "Lake Simcoe Junction Railway" just west of the Northern mainline outside of Toronto. This was one of several routes that planned to take advantage of the ports on Lake Simcoe that connected to the Trent-Severn Canal, greatly reducing the distance travelled by train.