1900-1909   #294-373

The early 1900s ushered in an attractive bicolor set of commemoratives showing the latest developments in transportation, a new highly-elaborate definitive series which was replaced by the Washington-Franklin series only 6 years later, and continued experiments in stamp production. Oklahoma became the 46th state in 1907, and the Louisiana Purchase Exposition stamps also came out in the early 1900s, both being important events in American history.