Sandy Hook Elementary School shooting. Adam Lanza shot and killed 20 children and 6 adults at the Sandy Hook Elementary School in Newtown, Connecticut.

Tanzania joins the United Nations. Tanzania was created as a merger of Tanganyika and the Zanzibar Archipelago, both of which were under British rule until independence.

Soviets Reach the Southern Pole of Inaccessibility. A Pole of Inaccessibility is a location on Earth that is extremely difficult to access. In the North, it is the point in the Arctic Ocean that is farthest from land, while in the Southern Hemisphere it is the point farthest from the Southern Ocean on Antarctica. In 1958, a Soviet team led by Yevgeny Tolstikov became the first people in history to reach the Southern Pole of Inaccessibility, which is 546 miles (878 kilometers) from the geographic South Pole. Temperatures at this location averages around – 73 degree F (–58 degrees C).

USSR expelled from the League of Nations. The Soviet Union was expelled from the League of Nations for making aggressive demands of Finland.

Roald Amundsen reaches South Pole. Norwegian explorer Roald Amundsen and his team reached the South Pole, becoming the first men in recorded history to set foot on the most southern point on Earth.