On this day in history, March 28, 1979, America's worst commercial nuclear accident took place at the Three Mile Island plant near Middletown, Pennsylvania.
The accident occurred when problems with the plant reactor's cooling system exposed part of the reactor's core, allowing radiation to escape into the air. Pennsylvania Governor Richard Thornburgh ordered the closing of 23 area schools and urged local residents to stay indoors. Although evacuation was not mandatory, pregnant women and small children were advised to leave. Several thousand children and over 100 pregnant women sought shelter in nearby Hershey, Pennsylvania. Opponents of nuclear power held a protest on April 1, 1979.