The presence of the Overland logo on the first two blotters here date them from 1942 or before. The other three blotters are probably from after World War II. All are from the Dale Hastin collection and the PDFs are about 200 to 300 KB in size.
Union Pacific evidently did a series of blotters tying itself to major state universities in the states it served. The Overland legend is clearly visible behind the UofI I.
The Washington State cougar obscures most of the Overland legend, but it is there. This dates these blotters since UP stopped using that logo in 1942.
The locomotive in the winged streamliner logo is clearly of the M-10003 to M-10006 series of trains, which came out in 1936. But UP used that logo for years after it replaced the automobile-style locos with bulldog-style.
Here’s another blotter with the same winged streamliner logo.
The City of St. Louis began operating in 1946, so this blotter dates from that year or later. The arrangement of text above, rather than below, the logo could indicate that the previous two blotters are from an earlier (or at least different) year.