There's nothing more evocative than browsing through a stack of historic photographs ... and nowadays a number of museums and archives are making their photo collections available on the Internet, which is a truly wonderful thing. There are a number of online repositories of Montana-related images, and while a couple of them are really badly done (I'm looking at you, Livingston), most of them are great, good for hours of nostalgic browsing.
One of my favorite such sites is maintained by the Museum of the Rockies, which holds the photo collection of the late Ron Nixon, one of the state's greatest railroad photographers. There are over 20,000 images in the Nixon collection, and the Museum has put nearly 12,000 of them online ... mostly from Montana, and mostly quite intriguing.
Here's a photo from the Nixon collection that's one of my favorites -- it's a shot of a Northern Pacific coal train heading out of Forsyth on February 20, 1939.