Next year will be the 150th anniversary of the Golden Spike at Promontory Point, which means these stamps, issued for the 75th anniversary, are themselves almost 75 years old. The Union Pacific logo is flanked by locomotive 119 on the left and an E6 locomotive, used on the City of Los Angeles and City of San Francisco, on the right.
Click image to download a 340-MB PDF of these stamps.
A note at the top urges people, presumably UP employees and agents, to “Use these poster stamps on your business and personal mail.” The stamps also advertise Your America, an NBC radio show sponsored by Union Pacific that was advertised using a series of paintings commissioned by Union Pacific. The PDF includes a brown sheet of coated paper designed to keep the stamps from unintentionally sticking to something else.