1. March 31, 1885 - Tucson's Youngest Mayor
On March 31, 1885, John M. Murphy was elected as the mayor of Tucson at the age of 22, making him the youngest person to hold the position in the city's history.

2. March 31, 1913 - Arizona's First Execution
On March 31, 1913, Arizona carried out its first execution, using the newly installed gas chamber. The inmate, M.A. Simmons, was convicted of killing his wife and two sons.

3. March 31, 1934 - Hoover Dam Construction Begins
On March 31, 1934, construction began on the Hoover Dam, one of the most famous landmarks in Arizona and the United States. The dam was completed in 1936 and remains one of the largest producers of hydroelectric power in the country.

4. March 31, 1942 - Japanese-American Internment Begins
On March 31, 1942, the U.S. government ordered the internment of approximately 120,000 Japanese-Americans, many of whom were living in Arizona at the time. They were forced to leave their homes and businesses and were held in internment camps for the duration of World War II.

5. March 31, 1990 - Phoenix Lights
On March 31, 1990, a massive UFO sighting occurred in Phoenix, Arizona. Thousands of residents reported seeing a series of strange lights moving across the sky in formation. The event remains one of the most famous UFO sightings in history.