I can find state by state and some regional rail trail maps but not one big bicycle route and trail atlas for the whole US and Canada. If there is not one should somebody (perhaps me or my bike club) write one?
By far the best one is published by the adventure cycling association. I bought their entire collection for the usa for about 70 bucks a few years ago.
Each map details the major routes around the usa (i think they have ones for Mexico and Canada too) and the maps give you elevation, dangerous shoulder warnings/locations, places to camp, get supplies, etc. Basically everything you would want to know.