As a Subscriber you will see all 161 images which will give you a far better sense of what was happening within a single year. At the moment you can see 10.
1969, Book cover for Barry B. Combs, 1969, Westward to Promontory: Building the Union Pacific across the plains and mountains. A Pictorial Documentary, (New York: Garland Books), Book cover, Jeffrey Kraus Antique Photographics, LL/84987