1. In 1911, the Navajo Nation was officially recognized as a sovereign nation by the United States government. The Navajo Nation is the largest Native American tribe in the United States and is located in Arizona, New Mexico, and Utah.

2. On January 18, 1936, the Hoover Dam was completed after five years of construction. The Hoover Dam is located on the Colorado River on the border between Arizona and Nevada and provides hydroelectric power and water to millions of people in the region.

3. In 1974, the Wickenburg Massacre occurred in Arizona, in which six people were killed by a group of criminals. The incident led to a renewed focus on law enforcement and border security in the state.

4. On January 18, 1993, the Martin Luther King Jr. holiday was recognized for the first time in Arizona. The holiday is celebrated on the third Monday in January and honors the life and legacy of civil rights leader Martin Luther King Jr.

5. In 2010, a 7.0 magnitude earthquake struck Haiti, causing widespread damage and loss of life. Many people in Arizona and throughout the United States participated in relief efforts to assist those affected by the earthquake.