1. Arizona became a US territory: On March 21, 1863, Arizona officially became a US territory, which paved the way for statehood in 1912. This was a significant turning point in Arizona's history as it marked the beginning of its integration into the United States.

2. The Chandler Post Office massacre: On March 21, 1991, a disgruntled postal worker opened fire in the Chandler post office, killing four people and injuring six others. It was one of the deadliest workplace shootings in US history at the time and highlighted the issue of gun violence in the workplace.

3. The Tuskegee Airmen: On March 21, 1945, the Tuskegee Airmen, an all-black squadron of fighter pilots, flew their last mission of World War II. Despite facing discrimination and prejudice, the Tuskegee Airmen played a crucial role in the war effort and helped pave the way for greater racial equality in the US Armed Forces.

4. The founding of Phoenix: On March 21, 1868, a group of settlers led by Jack Swilling founded the city of Phoenix. The founders were drawn to the area for its fertile land and abundant water supply, which made it an ideal location for agriculture and ranching.

5. Arizona celebrates its centennial: On March 21, 2012, Arizona celebrated its 100th anniversary of statehood. The year-long celebration included events and activities across the state, highlighting Arizona's rich history and culture.