Mountain City, Col., Jun 18, '65, cds and target duplex on 10¢ green entire to Eastchester, N.Y.; horizontal fold at top from when mailed and reduced at left, F.-V.F., a scarce 10¢ 'Trans-Mountain' rate usage during the interruption of mail service. Estimate  $150 - 200. Beginning in May 1865 and for much of the summer, Indian depredation along the South Platte River prevent regular mail services to the east. Mail was sent west on the Overland Trail to California then east. Therefore a 10 cents Trans-Mountain rate was charged. $0 (Image)