The train portrayed on the front of this ticket envelope looks like the Empire Builder between 1955, when the dome cars were added to the train, and 1962, when GN simplified the locomotive color scheme by deleting the bottom orange stripe. In fact, inside the envelope is a ticket for a trip on the Empire Builder from Everett to Spokane dated July 1, 1961.
Inside the envelope, the ticket agent has noted a fare for this trip of $60.35 plus a 10 percent tax of $6.04. Adjusted for inflation to today’s money, the total is more than $400. From SeaTac to Spokane, airfares today start at around $124, including tax.
I have similar envelope that prices someone’s trip from Chicago to Spokane: a fare of $428.18, tax of $89.43 (why 20 percent instead of 10?), accommodations of $89.43 (is it a coincidence or a mistake that it is identical to the tax?), plus some unspecified charge of $32.07, for a total of $639.11. Considering that the 1959 round-trip fare was just $168, including a roomette, the $639 fare must be for an entire family rather than just one person.