The FAA and NavCanada have established North American Routes. They are listed in the northeast volume of the FAA Airport Facilities Directory in the supplemental section. The formatting won't allow me to cut and paste. The NARs are normally two parts. There will be handful of routes from the end point of the NAT to another waypoint, most of them just direct. From BANCS it lists six or seven transitions including direct WHALE and direct BRADD. Then further in the listing are routes from these fixes to major airports. A route is given from BRADD to KFLL and also KMCO.