On this day: April 18

Runner Misses Course, Finishes Miles Off Route in 1980 Marathon

During the April 18, 1980 marathon, a competitor took a wrong turn and completed several miles off the official course, altering their finish time and sparking questions about course signage and oversight.

The 1956 Dartmouth Workshop: First Public Demonstration of AI Concepts

On April 18, 1956, researchers at Dartmouth College convened a workshop that articulated the formal research program for “artificial intelligence,” presenting early demonstrations of symbolic problem solving and proposing research directions that shaped the field.

1906 San Francisco Earthquake and Fire Devastate the City

On April 18, 1906, a major earthquake and the resulting fires struck San Francisco, causing widespread destruction, thousands injured or homeless, and fundamentally reshaping the city's landscape and recovery efforts.

First Spacewalk: Alexei Leonov Returns Safely After Historic EVA

On 18 April 1965, Soviet cosmonaut Alexei Leonov conducted the first human extravehicular activity and re-entered his Voskhod 2 spacecraft safely after a tense, improvised recovery that has since become a landmark of early spaceflight.