1) On September 23, 1806, the Lewis and Clark Expedition returned to Oregon's Fort Clatsop after completing their exploration of the western United States. The expedition was commissioned by President Thomas Jefferson, and helped to map and establish American claims to the region.

2) In 1862, the first Homestead Act land grant was issued in Oregon on September 23. The Homestead Act of 1862 provided free land to settlers who agreed to develop and improve it, helping to populate and develop the western United States.

3) On September 23, 1905, the first Rose Festival was held in Portland, Oregon. The festival, which is still held annually, celebrates the region's abundant roses and includes parades, concerts, and other events.

4) In 1962, President John F. Kennedy visited Oregon on September 23 to address a crowd of over 40,000 people at the University of Oregon in Eugene. Kennedy spoke about the importance of education and science, and his speech helped to rally support for his administration's policies.

5) On September 23, 1992, the Oregon Zoo's famous elephant, Packy, celebrated his 30th birthday. Packy was the first elephant born in captivity in North America, and was a beloved fixture at the zoo for decades before his death in 2017.