1775    The Spanish establish a ''presidio'' (fort) in the town that became Tucson, Arizona.

1856    American Old West: On the Sonoita River in present-day southern Arizona, the United States Army establishes Fort Buchanan in order to help control new land acquired in the Gadsden Purchase.

1863    Arizona is organized as a United States territory.

1868    Treaty of Bosque Redondo is signed allowing the Navajos to return to their lands in Arizona and New Mexico.

1886    Indian Wars: after almost 30 years of fighting, Apache leader Geronimo, with his remaining warriors, surrenders to General Nelson Miles in Arizona.

1912    Arizona is admitted as the 48th U.S. state.

1917    World War I: The U.S. ambassador to the United Kingdom is given the Zimmermann Telegram, in which Germany pledges to ensure the return of New Mexico, Texas, and Arizona to Mexico if Mexico declares war on the United States.

1935    The Hoover Dam, astride the border between the U.S. states of Arizona and Nevada, is dedicated.

1953    Arizona Governor John Howard Pyle orders an anti-polygamy law enforcement crackdown on residents of Short Creek, Arizona, which becomes known as the Short Creek Raid.

1956    A TWA Super Constellation and a United Airlines DC-7 (Flight 718) collide above the Grand Canyon in Arizona, United States, killing all 128 on board the two planes.

1962    The Petrified Forest National Park is established in Arizona.

1988    Governor Evan Mecham of Arizona is convicted in his impeachment trial and removed from office.

1995    An Amtrak Sunset Limited train is derailed by saboteurs near Palo Verde, Arizona.

1999    The State of Arizona executes Karl LaGrand, a German national convicted of murder during a botched bank robbery, in spite of Germany's legal action to attempt to save him.