Denver City, K.T., Feb 11, 1861 "Tombstone" Postmark (Unorganized Territory), bold full serifed postmark (third type) on cover to Oswego, Ind., franked with 1857, 3¢ dull red canceled by grid handstamp; cover slightly reduced at left and stamp with minor corner nick at bottom right, still Very Fine, a rare usage of the Denver City K.T. Tombstone date stamp used after Kansas had become a state on January 29th and before the formation of Colorado Territory on February 28th of 1861. Estimate  $750 - 1,000. $0 (Image)