The National Association of Railroad Passengers, a passenger rail lobby group, has a collection of maps showing the change in Amtrak route coverage since the national rail carrier was created in 1971. The PDF maps are rather basic, and show overall routes (unlabelled) and frequencies, rather than individual stops. (“Non-Amtrak service” means passenger trains run by the Denver & Rio Grande Western and the Southern before their services were folded into Amtrak, and CP Rail/VIA Rail service across Maine.)