High Quality Content by WIKIPEDIA articles! The Oklahoma Statehood Stamp was issued on January 11, 2007 by the United States Postal Service (USPS) to celebrate the 100th birthday of the entry of the U.S. state of Oklahoma into the Union (Oklahoma became the 46th state on November 16, 1907). The stamp is part of a series of stamps which seek to commemorate the entry of new states into the Union; the USPS has also announced the sale of commemorative stamps for Alaska (stamps went on sale on January 9, 2009), Oregon (stamps went on sale January 14, 2009), and Hawaii (the stamps will go on sale in the summer of 2009).