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 United States completed its purchase of Alaska for $7.2 million, taking possession of the territory from Russia.
1962 – Dr. James D. Watson of the United States and Dr. Francis Crick and Dr. Maurice Wilkins of Britain were named winners of the Nobel Prize in Medicine for their work in determining the double-helix molecular structure of DNA.
1972 – Congress passed the Clean Water Act, overriding President Richard M. Nixon’s veto.