1) On December 15, 1913, Arizona officially became the 48th U.S. state, after a long fought battle to achieve statehood. The state was able to achieve statehood after adopting the Arizona Constitution, which was approved by U.S. Congress.

2) December 15 of 1904 is considered the coldest day in Arizona history. The temperature dropped to -40 °F (-40 °C) in Hawley Lake, breaking all previous records.

3) In the early 1900s, the city of Phoenix became a center for aviation, largely due to the efforts of pioneer aviator Glenn Curtiss. On December 15, 1910, Curtiss made the first recorded airplane flight in Arizona history.

4) On December 15, 1967, rancher Paul Isaak was abducted by three men in the town of Wickenburg, sparking a wave of similar kidnappings in the area. The culprits were eventually revealed to be members of the notorious Gambino crime family, and Isaak was eventually released unharmed after his family paid a ransom of $25,000.

5) December 15, 1905 marked the opening of the Arizona Biltmore Hotel, one of the most iconic landmarks in Phoenix. Designed by Albert Chase McArthur and Frank Lloyd Wright, the hotel was originally built as a desert getaway for wealthy East Coast travelers. Today, it remains a popular destination for tourists and locals alike.