1. On October 4, 1864, Colonel Kit Carson led a group of U.S. soldiers in a surprise attack on a Navajo stronghold known as Canyon de Chelly. This was part of the Navajo Wars, which lasted from 1850 to 1866 and resulted in the forced relocation of thousands of Navajo people to reservation land.

2. In 1878, the first post office in Tucson, Arizona was established on October 4th. Prior to this, mail service was irregular and unreliable. The post office helped to connect Tucson with the rest of the country and played a key role in shaping the city's development.

3. On October 4, 1927, the Arizona Theatre in Phoenix opened its doors for the first time. The theater, which still stands today, was designed by the noted Phoenix architect Lescher & Mahoney and featured state-of-the-art sound and projection equipment.

4. The Arizona State Fair, which has been held annually since 1884, officially opened on October 4 in 1935. The fair, which lasts for several weeks, is a major cultural event in the state and features live music, carnival rides, and agricultural expositions.

5. On October 4, 1988, a team of archaeologists working at the Casa Grande Ruins National Monument in southern Arizona discovered an ancient Hohokam ball court. This find shed new light on the Hohokam culture, which inhabited the area from about 300 to 1450 AD and is known for its advanced irrigation systems and elaborate pottery.