1. Arizona Became a State
One of the most significant events in Arizona's history occurred on September 7, 1912, when it officially became the 48th state in the United States.

2. Historic Earthquake
On September 7, 1910, an earthquake occurred in the area of Flagstaff, causing significant damage to the city and surrounding areas.

3. Launch of a Spacecraft
On September 7, 2007, NASA launched the Phoenix Mars Lander, which successfully landed on the Martian surface in May 2008. This marked the first time a NASA spacecraft had landed on Mars since the Mars Exploration Rover in 2004.

4. Signing of the Colorado River Compact
On September 7, 1922, representatives from seven Western states, including Arizona, signed the Colorado River Compact, which determined the allocation of water resources for the region.

5. The First Woman Elected to Congress
On September 7, 1949, Arizona's Isabella Greenway became the first woman in the state's history to be elected to the United States Congress. Greenway, a prominent figure in Arizona's business and political circles, served in Congress until 1953.