St. Paul's first automatic traffic signal, on a pedestal about ten feet high, begins operating at Fifth and St. Peter Streets.

Father Louis Hennepin, exploring the Mississippi River north from Illinois by canoe, is captured by a group of Dakota. During his captivity he sees Owamni Yomni, which he calls the Falls of Anthony (for his patron saint). On July 25, Daniel Greysolon, the Sieur Du Luth, arranged for Hennepin's release.

The ocean liner St. Paul is launched at last. The International Navigation Company had intended to launch the ship on March 25, inviting seventy dignitaries to Philadelphia for the occasion. After the champagne bottle was broken, however, the ship refused to budge.

Jacob Fjelde is born in Norway. He sculpted the work Hiawatha and Minnehaha, displayed in Minnehaha Park, Minneapolis, and the statue of Ole Bull located in Loring Park, Minneapolis.

The Andersen Library at the University of Minnesota opens, named in honor of Elmer L. Andersen, former governor, university regent, and bibliophile. Library materials from around the state are stored in two manmade caverns, each two stories high and two football fields long, carved into the sandstone bluffs along the Mississippi River.

Minnesota receives word that it is a territory of the United States, a month after the bill is approved by President James K. Polk.

Rose Ann Perry marries James Clewett in St. Paul's first Christian wedding, officiated by the Reverend J. W. Pope, a Methodist missionary at Kaposia.

Geographer David Thompson leaves the trading post of Jean-Baptiste Cadotte on Red Lake River, beginning the last part of his 4,000-mile survey of the northern wilderness, the first scientific study of the state. Beginning in Grand Portage in August 1788, he had traveled to the upper Missouri River and then through Minnesota, where he wintered with Cadotte. He completed his trip by returning to Grand Portage in June.

Responding to the first-ever sit-down strike at Minnesota State Prison in Stillwater, warden Carl Jackson meets the prisoners' demands for nourishing, sanitary food by firing the prison's chef. During the strike, which began on April 7, the locked-down prisoners littered the corridors with trash and broke a number of windows.

Melvin Calvin is born in St. Paul. Working as a biochemist decades later, Calvin discovered the details of the photosynthesis process, and was awarded a Nobel Prize in Chemistry in 1961.