| United States |
| (via Memphis) (1) |
| 1851 Inbound to Santa Fe (1) |
| Auraria, Kansas Territory (1) |
| Auraria, Kansas Territory, Willis' Last Contract M (1) |
| By Overland Mail (1) |
| C.O.C. & P.P. Express Label (1) |
| Camp Floyd, U.T. (1) |
| Central Overland Pony Express Company frank (1) |
| Completion of the Railroad, Nine Mile Gap Mail (1) |
| Denver City Tombstone Postmark, Aug 23 1860, Tempo (1) |
| Desert Dispatch "via San Diego" to Fort Yuma, 1855 (1) |
| Desert Dispatch to Fort Yuma, 1855 (1) |
| Earliest known letter from the Denver gold mining (1) |
| Eastbound Pony Express (1) |
| Eastbound Pony Express to Confederate Virginia (1) |
| First Eastbound Trip Overland Mail Company (1) |
| Fort Bridger, U.T. Straight Line (1) |
| Fort Bridger, Wyoming, 1857 (1) |
| Fort Laramie N.T. (Nebraska Territory) (1) |
| Fort Laramie O.R. crude "Oregon Route" (1) |
| Fort Laramie to Benicia (1) |
| Fort Laramie, DT, 1866 (1) |
| Frank of The Central Overland California & Pike's (1) |
| From Argentina Fourth Westbound OMC (1) |
| from London, too late for the Pony Express (1) |
| Grattan Massacre, Sent back to England (1) |
| Great Salt Lake City Cal. (1) |
| Hawaii to Utah, 1855 (1) |
| Hawaii via California and OMC Route to Blockading (1) |
| Hawaii via San Francisco and the Central Route, 18 (1) |
| Helena, Montana, 1868 (1) |
| Hinckley & Co's Express Denver City (1) |
| Holladay Overland Mail and Express Company, 1865 (1) |
| Jones & Russell's Pike Peak Express Co. (1) |
| Leavenworth City & Pike’s Peak Express (1) |
| Leavenworth City & Pike’s Peak Express, earliest k (1) |
| Minnesota to Denver City, Third Inbound Contract T (1) |
| OMC - Altered Text Stagecoach Directive (2) |
| OVERLAND (9) |
| Overland Mail Stage, Via Los Angeles (1) |
| Overland Mail via Placerville & Salt Lake (1) |
| Overland Mail, via Boise City (1) |
| Overland Mail, Via Los Angeles (1) |
| Overland via Central Route (1) |
| Overland Via Los Angeles (2) |
| Overland via Los Angeles, From E.S. Howell, San Fr (1) |
| Overland via Salt Lake (1) |
| Overland Via Visalia, Fort Tejon, Los Angeles, For (1) |
| Overland, via Los Angeles. (1) |
| Per Overland Mail Stage, Via Los Angeles (1) |
| Per Overland Mail via Placerville and Salt Lake, H (1) |
| Per Overland Mail, Via Los Angeles, In Hope of the (1) |
| Platte River Ferry, 1850 (1) |
| Pr Overland Mail Via Los Angeles (1) |
| Rockfellow & Co's Express Paid 50c to France (1) |
| Salt Lake City to Russia, 1856 (1) |
| Salt Lake City U.T, 1853 (1) |
| Salt Lake City U.T. (1) |
| Salt Lake City U.T. July 1, 1851 (1) |
| San Francisco, Via Los Angeles Overland (1) |
| Santa Fe, New Mexico (1) |
| Taos, NM, 1855 letter mentions Kit Carson (1) |
| The "Jackass" Route Defined by Postmarks (1) |
| The Central Overland California & Pike's Peak Expr (4) |
| The Deconstructed "Jackass" Route (2) |
| Via California Phantom Rate, 1855 (1) |
| Via over Land Mail Rout (1) |
| Via Overland Mail (1) |
| Via Overland St. Louis (1) |
| Via Southern Overland Mail (1) |
| Victoria, via California and OMC Route (1) |
| Virginia City Pony Express, 10c Blue imprinted ent (1) |
| Virginia City Pony Express, 10c Brown (1) |
| Westbound from Salt Lake City Utah T, 1851 (1) |
| Westbound Pony Express Franked Entire (1) |
| Westbound Pony Express to Oregon (1) |