1931: Border patrolmen discover the skeleton of a 25,000-year-old mammoth near Hereford.
1862: The advance guard of the California Column reaches Tucson under the command of Lt. Col. Joseph West and establishes Camp Lowell.
1892: A stage coach line is established between Flagstaff and the Grand Canyon.
1910: John Gardner, Pima County census enumerator, reports that as he entered a Yaquai village in northern Pima County all the Indians quickly vanished. His total count for the village was one female.
1900: An Arizona and New Mexico Railroad freight train crashes through a bridge near Clifton. Three people are killed and nine injured.
1898: Arizona barbers raise their prices to an unheard of high for a shave — 25 cents.
1899: The Phoenix Daily Herald runs an ad by a local contractor asking residents why they continue to spend $5, $10 or $15 a month on rent when they could own a lot in the heart of Phoenix for $65 to $200.
1884: The first Arizona Industrial Exposition is held in Phoenix.
1846: President James K. Polk declares a state of war exists between the United States and Mexico.
1886: Fire destroys Grand Central pumphouse in Tombstone, causing the mines to flood and shutting down all mining operations.
1889: A band of masked men ambushes Major J.W. Wham and his military escort carrying a $26,000 army payroll to Fort Thomas. The payroll was stolen and eight soldiers were wounded.
1863: The Pioneer Mining District on Lynx Creek is formed after five members of the party led by Captain Joseph Walker discover gold along Lynx Creek.
1540: Captain Juan Hernando de Alarcon leaves Acapulco, Mexico to sail north until he reached the headwaters of the Gulf of California, thus becoming the first white man to explore beyond the mouth of the Colorado River.
1900: President William McKinley spends a day in Phoenix, then makes a whistle-stop in Tucson. But he fails to mention the possibility of statehood for Arizona.
1872: The first lawyers are admitted to practice law in Maricopa County.
1896: The Bisbee Daily Review newspaper is established.
1910: Tucson citizens celebrate the opening of the Tucson-West Coast of Mexico Railroad.
1883: Andrew W. Holbrook becomes the first Pima County Sheriff's Department employee to die in the line of duty. Head jailer at the Pima County Jail, Holbrook is shot in the back by one of two prisoners attempting to escape. Though gravely wounded, he holds the jail's door closed until help …
1882: President Chester A. Arthur warns Arizona that he would place it under martial law unless it shows more respect for law and order. The warning was directed chiefly at Cochise County.
1872: Two earthquake shocks are felt in Yuma at 5:45 p.m.
1859: Father Joseph P. Machebeuf is named the first American Catholic priest in Arizona.
1871: Six Americans, 48 Mexicans and 92 Papago Indians from Tucson kill 118 Aravapia Apaches — mostly women and children — who had surrendered to the Army at Camp Grant, a military outpost north of Tucson. It becomes known as the Camp Grant Massacre. Twenty-seven Apache children were kidnapp…
1904: The first meeting of the Arizona Automobile Association opens in Tucson with a parade and a visit to the San Xavier Mission.
1700: Father Eusebio Francisco Kino writes in his diary that work had begun on the foundations of the first church at Mission San Xavier del Bac.
1887: At Pantano, east of Tucson, outlaws pull the first train robbery recorded in Arizona history.