1872 On September 26, 1872, an agreement was made with the Shoshone by which they ceded to the United States that part of their reservation "south of a line beginning at a point on the eastern boundary of the reservation due east of the mouth of the Little Popo-Agie at its junction with the Popo-Agie and running from said point west to the mouth of the Little Popo-Agie; thence up the Popo-Agie to the north fork and up the north fork to the mouth of the canyon; thence west to the western boundary of the reservation."
1876 On September 26, 1876 a treaty with the Sioux people ceded to the United States all that part of Wyoming north of the Platte and Sweetwater, and extending west to the Rattlesnake mountains and the Powder river, was ceded to the United States. Congress promptly ratified the agreement and the lands were opened to settlement. Most of the counties of northeastern Wyoming were formed out of the lands obtained by this treaty.
1908 Tower Post Office in Crook County was established on September 26, 1908.
1918 News about the Big Horn Basin.
1924 Rex Post Office in Albany County, was established on September 26, 1924.
1906 On September 24, 1906, President Theodore Roosevelt proclaimed Devils Tower as a National Monument. It was America's first National Monument.
1907 Kendrick Post Office in Sheridan County was established on September 24, 1907. Named for the late senator, John B. Kendrick, Kendrick was also a station on the Chicago, Burlington and Quincy Railroad.
1967 The Tri-Territory Historical Marker was dedicated on September 24, 1967.
1967 The Goodstein Foundation Library of Casper College was dedicated on September 24, 1967.