- 1776 – The border between Maryland and Pennsylvania was established. Dubbed the “Mason-Dixon” line, it became the unofficial boundary between North and South.
- 1867 – The U.S. takes possession of Alaska after purchasing it from Russia for $7.2 million.
- 1898 – The U.S. takes possession of Puerto Rico from Spain.
- 1954 – Texas Instruments announces the first transistor radio.
- 1959 – The Soviet Union announced that Luna 3, an unmanned space vehicle, had taken the first pictures of the far side of the moon.
