Signed in the Mexico City suburb of Guadalupe Hidalgo, the treaty ceded present-day California, Nevada, Utah, and parts of Arizona, New Mexico, Colorado, and Wyoming to the United States for $15 million. The transfer reshaped the map of North America, displacing tens of thousands of Mexican citizens and Indigenous peoples and setting the stage for later debates over slavery's expansion into the new territories.

Newspaper editor Clymer Freas and a group of local groundhog hunters known as the Punxsutawney Groundhog Club declared February 2 an annual weather-prediction ritual, borrowing from German-immigrant Candlemas lore that a hibernating animal's shadow foretold six more weeks of winter. The whimsical local custom eventually grew into a national media spectacle broadcast from Gobbler's Knob every year.

Sylvia Beach's Shakespeare and Company bookshop published the complete edition of 'Ulysses' in Paris, delivering Joyce's dense, stream-of-consciousness reimagining of Homer's Odyssey set across a single day in Dublin. The novel had been serialized and then suppressed in the United States after obscenity charges, and it remained banned there until a landmark 1933 court ruling lifted the prohibition.

After nearly six months of house-to-house fighting in freezing ruins, Field Marshal Friedrich Paulus's encircled Sixth Army capitulated to Soviet forces. Some 91,000 starving German soldiers were taken prisoner; fewer than 6,000 would ever see Germany again. The defeat shattered the myth of Wehrmacht invincibility and turned the tide of World War II.

Following its launch on January 31, 1958, Explorer 1 began transmitting data that physicist James Van Allen used to identify bands of energetic charged particles trapped by Earth's magnetic field. The discovery, one of the first major scientific results of the space age, reshaped understanding of the planet's magnetosphere and the radiation hazards facing future astronauts.

Having overthrown President Milton Obote while he was abroad, army commander Idi Amin consolidated his takeover by declaring himself head of state, suspending sections of the constitution, and dissolving parliament. His rule would descend into mass killings, the expulsion of Uganda's Asian minority, and economic collapse before his ouster in 1979.