Near my hometown, there is a place called, "The Ghost Town Trail" which is basically a hiking/biking trail that is roughly 32-36 miles long (the main branch runs East to West with extensions added throughout the past two decades since it was first created). It got its name because there used to be a railroad that would pass through old ghost towns that were left abandon roughly around 1900.
Here is one of the sites- it's called "Buena Vista Furnace" this one, in my opinion, is the easiest best site to bike to (from my hometown). Other sites would be just a sign and/or a plaque given a brief history of the former ghost town.
