1. On September 23, 1783, George Washington, who was at that time the commander-in-chief of the Continental Army, visited Portsmouth, New Hampshire. Washington traveled to Portsmouth to meet with the Continental Congress and discuss the state of the newly-formed United States of America.

2. September 23, 1889, marked the opening of the New Hampshire State Fair. The first iteration of the fair was held in Manchester, and it has since become an annual tradition that takes place in Durham.

3. The first American smokeless powder was created on September 23, 1898, by the DuPont Company in New Hampshire. The powder was a significant advance over traditional gunpowder, as it produced fewer harmful pollutants and provided a cleaner burn.

4. On September 23, 1959, the U.S. Postal Service introduced zip codes for mail delivery, which became a vital tool for sorting and delivering mail efficiently. The first zip code in New Hampshire was assigned to the city of Manchester, which was designated 03101.

5. In 1996, a massive flood devastated parts of northern New Hampshire, causing tens of millions of dollars in damage and claiming several lives. The flooding, which occurred on September 23 and 24, was caused by heavy rainfall and flash flooding, and it remains one of the state's most significant natural disasters.