North American Overlay Mapping
Layer Notes - Roads and Rail
The 'Road' foreground overlay shows the presence and location of major roads throughout North America. In the USA, the roads shown are the 'Interstates' and the 'US Routes', differentiated with orange and blue colors. In Canada and Mexico, no direct equivalent of these exists, so the choice was made to assign the same colors to major and medium priority routes.
The 'Rail' foreground overlay shows the railroad routes from the National Transportation Atlas Database maintained by the Federal Railroad Administration, available from the Bureau of Transportation Statistics (BTS). No attempt has been made to identify any of the routes.