1841 – US President Harrison died of pneumonia after one month in office
1850 – Los Angeles, California was incorporated as a city.
1871 – Mary Florence Potts of Ottumwa, Iowa Patented (#113,448) the “Mrs. Potts’ sad iron” – a set of three irons with a detachable handle, so two irons could be heating up while you were using the other.
1877 -A pianist performed in Philadelphia, and an audience heard the performance in New York, via the telephone.
1932 – Professor C. Glen King, of the University of Pittsburgh, discovered vitamin C.
1933 – Akron, a dirigible, crashed in New Jersey, killing 73 people.
1949 – Twelve nations signed the North Atlantic Treaty, creating the North Atlantic Treaty Organization (NATO).
1964 – #1 Hit April 4, 1964 – May 8, 1964: The Beatles – Can’t Buy Me Love
1964 – The Beatles occupied all of the top five positions on the Billboard singles chart in the United States, with Can’t Buy Me Love, Twist and Shout, She Loves You, I Want to Hold Your Hand, and Please Please Me.
1968 – Martin Luther King, Jr was assassinated by James Earl Ray in Memphis Tennessee.
1969 – CBS abruptly cancelled The Smothers Brothers Comedy Hour, and replaced it with Hee Haw. Hee Haw episodes were ready to premiere in mid-June.
1973 – The World Trade Center in New York was officially dedicated.
1975 – Microsoft was founded as a partnership between Bill Gates and Paul Allen in Albuquerque, New Mexico
1983 – Space Shuttle Challenger made its maiden voyage into space (STS-6).
1987 – #1 Hit April 4, 1987 – April 17, 1987: Starship – Nothing’s Gonna Stop Us Now
1998 – #1 Hit April 4, 1998 – April 24, 1998: K-Ci & JoJo – All My Life
2013 – Famed movie critic Roger Ebert died