1812 – President James Madison enacts a ninety-day embargo on trade with the United Kingdom.
1818 – Congress adopts the flag of the United States with 13 red and white stripes and one star for each state (then 20).
1841 – President William Henry Harrison dies of pneumonia, becoming the first President of the United States to die while in office, and setting the record for the briefest administration, serving just one month in office. Vice President John Tyler succeeds Harrison as President.
1850 – Los Angeles is incorporated as a city.
1887 – Argonia, Kansas elects Susanna Madora Salter as the first female mayor in the United States.
1949 – Twelve nations sign the North Atlantic Treaty creating the North Atlantic Treaty Organization (NATO).
1968 – Martin Luther King Jr. is assassinated by James Earl Ray at a motel in Memphis, Tennessee.
1975 – Microsoft was founded by Bill Gates and Paul Allen.
1988 – Governor Evan Mecham of Arizona is convicted in his impeachment trial and removed from office.