AP US History This Day in American History September The Judiciary Act of 1789 is passed by Congress and signed by President George Washington, establishing the Supreme Court of the United States as a tribunal made up of six justices who were to serve on the court until death or retirement.

AP US History This Day in American History September – Motorcycle builder Soichiro Honda incorporates the Honda Motor Company in Hamamatsu, Japan. In the 1960s, the company achieved worldwide fame for its motorcycles (in particular, its C100 Super Cub, which became the world's best-selling vehicle); in the 1970s, it achieved worldwide fame for its affordable, fuel- efficient cars.

AP US History This Day in American History September – President Lyndon B. Johnson receives a special commission's report on the assassination of President John F. Kennedy, which had occurred on November 22, 1963, in Dallas, Texas.

AP US History This Day in American History September – Blockbusting bestselling author Stephen King releases two new novels at once. The first, Desperation, was released under King's name, while the second, The Regulators, was published under his pseudonym, Richard Bachman.