1959 Gainesville Midland Railroad Cover?

This is my first post, as my mother just recently found and gave me my grandfather's stamp collection. I've been going through it and finding them very interesting, so I've started cataloging everything and I'm trying to learn a bit about what I've got. Part of the collection is a huge stack of covers. All of them are 1st day of issue except for this one. Its from 1959 and reads "This cover was carried aboard the last steam operated passenger train in the state of Georgia". It has 2 different stamps on it. I've looked around online and haven't found another one like it, so was curious if any of y'all are familiar with it or know anything about it, such as how these were obtained, does it have any collectible value, etc.
Thanks very much,
Meredith

The late 1950s marked the end of regular mainline use of steam locomotives on virtually all railroads in America, as steam was replaced by more efficient diesel-electric locomotives. "End of steam" excursions for railfans, or other "last run of steam" commemorations, occurred regularly in the period 1955-1960. Typically several hundred people rode or photographed the train, but not all were interested in stamps. Thus, for this particular type of cover, there could have been from a few dozen to a few hundred created and distributed. This cover is not addressed, so it was probably canceled to order at Athens and then placed aboard the train, and sold onboard or at one endpoint.

The cover shows staining. The stamps are common types that had been issued in years prior to 1959 and were selected just because they were available and had railroad themes. The stamps alone are not valuable, and for many, the fact that the cover probably was not genuinely postally used--that is, mailed and carried to someone--reduces its value. Covers of this type typically sell for $3 to $25 depending on how much a particular individual wants to have one.

This particular cover could be of interest to Georgia railfans or those with interest in the history of smaller towns in Georgia or of Athens in particular. One of my kids is at UGA there. Athens no longer has passenger service, but has continuing through freight service to supply a coal power plant. The railroads around Athens are single-track and picturesque. A wood trestle in Athens, now unused and decaying, was featured on the cover of one of the albums of the band R.E.M. in its early years. These factors might increase the buyer population.

Thanks for the information- that was pretty much everything I wanted to know! It looks like the majority of the covers I have were never actually addressed & sent, aside from a bunch from the 50's that my grandfather evidently mailed to my father (which I find sort of funny because my dad was born in 1950, so I'm sure he enjoyed receiving them!). Originally, I didn't expect to keep his collection, and regardless I want to know the value of the items, but while learning about his stuff (I'd never even heard of covers before), I keep finding stamps that he didn't have that intrique me for one reason or another and end up buying them to add to his, so I suppose it's all become mine for good now! Thank you again.