Photo 2 looks like part of the series taken by the Denver Water Board, I think in 1929. I nolonger have all my South Park books, so someone else will have to confirm that.
Photo 3 is just a guess - one of those Depression era CCC specials, given a double headed all-passenger consist.
Cheers,
Ralph
“My heart is warm with the friends I make, And better friends I’ll not be knowing;
Yet there isn’t a train I wouldn’t take, No matter where it’s going.”
- - - - - - - “Travel”, by Edna St. Vincent Millay