September 1

1899 Hazelton Post Office in Johnson County was established on September 1, 1899.

1921 Yoder Post Office in Goshen County was established on September 1, 1921.

1942 The Casper Army Air Base was activated on September 1, 1942. It was officially deactivated on March 7, 1945, and is now incorporated into the Natrona County International Airport. It is also listed on the National Register of Historic Places.