1. AP US History This Day in American History November 20 1789 – New Jersey ratifies the Bill of Rights, becoming the first state to do so. New Jersey's action was a first step toward making the first 10 amendments to the Constitution law and completing the revolutionary reforms begun by the Declaration of Independence.

2. AP US History This Day in American History November 20 1923 – The U.S. Patent Office grants Patent No. 1,475,074 to 46-year-old inventor and newspaperman Garrett Morgan for his three-position traffic signal. Though Morgan's was not the first traffic signal (that one had been installed in London in 1868), it was an important innovation nonetheless: By having a third position besides just "Stop" and "Go," it regulated crossing vehicles more safely than earlier signals had.

3. AP US History This Day in American History November 20 1967 – San Jose State College students demonstrate against the Dow Chemical Company, the maker of napalm. Police were sent in, but the students refused to disperse and several protest leaders were arrested. The next day the students defied California governor Ronald Reagan's warning against further demonstrations and again staged an anti-Dow demonstration.

4. AP US History This Day in American History November 20 1968 - Methane gas explosions in a West Virginia coal mine kill 78 men on this day in 1968. The damage to the mine was so extensive that it had to be sealed with the bodies of the men still inside.