1870: Charles T. Hayden organizes the Hayden Milling and Farming Ditch Co., and prepares to establish a ferry and mill on the south side of the Salt River, the site of which was to become the City of Tempe.

1940: A parade to celebrate the "Arizona" movie premiere — including the film's stars, William Holden and Jean Arthur — meanders through Downtown Tucson.

1951: A bell salvaged from the USS Arizona, which was destroyed at Pearl Harbor on Dec. 7, 1941, is rung for the first time in the clock tower of the new Memorial Student Union Building. For the next 50 years, the bell was rung on special occasions until the clock tower and Student Union were razed to make way for the present-day facility, which was completed in 2002.

Want to share an important event from Tucson's history? Email it to krumore@azstarnet.com.