On This Day in History

Jonas Salk announced the successful test of his polio vaccine on a small group of adults and children.

A group of peasant women in Chamoli district, Uttarakhand, India, surrounded trees in order to prevent loggers from felling them, giving rise to the Chipko movement.

The Biological Weapons Convention, the first multilateral disarmament treaty banning the production of an entire category of weapons, entered into force.

Singapore Airlines Flight 117 was hijacked by four Pakistani terrorists and diverted to Changi Airport.

Police in Rancho Santa Fe, California, discovered the bodies of 39 members of the religious group Heaven's Gate who had died in an apparent cult suicide.

A jury began deliberations in the trial of Jack Kevorkian, an American practitioner of physician-assisted suicide who was charged with murder in the death of a terminally ill patient.

A prototype of the Tesla Model S, one of the most influential electric cars in history, was unveiled.

An explosion, allegedly caused by a North Korean torpedo, sank the South Korean warship ROKS Cheonan near Baengnyeongdo in the Yellow Sea, killing 46 sailors.

The Francis Scott Key Bridge collapsed following a collision between the MV Dali container ship and one of the bridge's support pillars, killing 6 people.