1947  —  Jackie Robinson makes his major league debut.
 
  

• The Buffalo Springfield perform for the first time, opening for the Byrds in San Bernardino, California, 1966

1924 – Rand McNally publishes its first road atlas.

2003 – The Human Genome Project is completed with 99% of the human genome sequenced to an accuracy of 99.99%.

1939 – The Grapes of Wrath, by American author John Steinbeck is first published by the Viking Press.

1992 – The Great Chicago flood devastates much of central Chicago.

1970 – An oxygen tank aboard Apollo 13 explodes, putting the crew in great danger and causing major damage to the spacecraft while en route to the Moon.

1953 – CIA director Allen Dulles launches the mind-control program Project MKUltra.

1870 – The New York City Metropolitan Museum of Art is founded.

1976 – The Apple I is created.

1970 – Paul McCartney announces that he is leaving The Beatles for personal and professional reasons.

1925 – The Great Gatsby by F. Scott Fitzgerald is first published in New York City, by Charles Scribner's Sons.

1866 – The American Society for the Prevention of Cruelty to Animals (ASPCA) is founded in New York City by Henry Bergh.

1815 – The Mount Tambora volcano begins a three-month-long eruption, lasting until July 15. The eruption ultimately kills 71,000 people and affects Earth's climate for the next two years.

1974 – At Atlanta–Fulton County Stadium, Hank Aaron hits his 715th career home run to surpass Babe Ruth's 39-year-old record.

1911 – Dutch physicist Heike Kamerlingh Onnes discovers superconductivity.

• Alice Cooper nearly hangs himself for real at a concert rehearsal in London when a safety rope breaks, 1988

1933 - Sales of beer in the U.S became legal on April 7, 1933, in states that had enacted their own law allowing such sales. The beer had to have an alcohol content less than 3.2% by weight (4% by volume), compared to the 0.5% limit of the Volstead Act, because 3.2% was considered too low to produce intoxication. On the evening of April 6, people lined up outside breweries and taverns, waiting for midnight when they would be able to legally purchase beer for the first time in over 13 years. Since then, the night of April 6 has been referred to as "New Beer's Eve" and April 7 is known as "National Beer Day".
 

1969 – The Internet's symbolic birth date: Publication of RFC 1.

1967 – Film critic Roger Ebert published his very first film review in the Chicago Sun-Times.