This colorful envelope features the full-length dome of the late-1950s Empire Builder. Someone apparently used this for a round-trip from Spokane to Chicago.
Traveling in October, 1959, the round-trip fare was $117.70 plus $50.50 for a roomette, which is a little over $1,000 today. The envelope didn’t come with a complete ticket, but the Pullman portion of the ticket shown below makes it clear that the accommodation charge, including tax, was $25.25 each way. For comparison, a one-way, six-hour (including one change of planes) airline trip from Spokane to Chicago today starts at under $130.