1. The Battle of Harlem Heights took place on September 17, 1776, during the American Revolution. It was a significant victory for the Continental Army, as they were able to hold their ground against the British forces and gained a morale boost.

2. On September 17, 1787, the United States Constitution was signed in Philadelphia. However, it was not until the following year that New York ratified the document, becoming the eleventh state to join the Union.

3. In 1859, Joshua Norton, a former San Francisco businessman, declared himself the "Emperor of the United States" in New York City. While his claim was not recognized by the government, he became a beloved figure in the city and was often given free meals and tickets to events.

4. On September 17, 1920, a horse-drawn wagon filled with explosives was detonated on Wall Street, killing 38 people and injuring hundreds more. The bombing, which was later attributed to anarchists, is considered one of the deadliest terrorist attacks in U.S. history up until the 1995 Oklahoma City bombing.

5. The first edition of The New Yorker magazine was published on September 17, 1925. The publication has become known for its satirical cartoons, insightful essays, and in-depth reporting, making it a staple of New York City culture.