1. The Louisiana Purchase: On May 25, 1803, the United States and France signed the Louisiana Purchase treaty, which transferred over 530 million acres of land from France to the United States, including the entire state of Louisiana.

2. First Class Graduates from LSU: In 1869, the first class graduated from Louisiana State University. The graduating class consisted of three students: Henry A. M. Gray, Clarence B. Jones, and William L. McMillan.

3. Hurricane Camille: On May 25, 1969, Hurricane Camille formed in the Gulf of Mexico and made landfall along the Mississippi coast. The storm caused widespread devastation across the Gulf Coast, including Louisiana, and was one of the most intense hurricanes to ever hit the United States.

4. World War II: In 1944, on May 25, General Dwight D. Eisenhower visited the Louisiana Maneuvers Military Base. Louisiana was an important center for military training during World War II, and the state was home to several military bases.

5. Jazz Fest: The New Orleans Jazz and Heritage Festival, also known as Jazz Fest, typically takes place in late April and early May each year. However, in some years, the festival has been held into late May, including in 1986 when it ended on May 25. Jazz Fest is a celebration of New Orleans' music, food, and culture and is one of the most popular events in Louisiana each year.