1877: The first Mormon settlers arrive on the San Pedro River to find what is now the town of St. David.
1927: The Colorado River changes course below Yuma and the United States gains 600 acres of Mexican land.
1934: A Thanksgiving Day record low of 23 degrees is recorded in Tucson.
1949: Actor Garry Shandling, who was raised in Tucson and attended the University of Arizona, is born in Chicago.
1956: Firefighters rescue seven in blaze at Cele Peterson's store; $500,000 in damage.
Want to share an important event from Tucson's history? Email it to firstname.lastname@example.org.