1. In 1857, the Massachusetts State Legislature granted a charter to the Boston Park Commission to establish and maintain a system of public parks and open spaces throughout the city. This led to the creation of iconic parks like Boston Common and the Emerald Necklace.

2. On May 31, 1888, John J. Montgomery made the first controlled flight in the United States in his homemade glider above Otay Mesa, California. Montgomery, who was born in Yuba City, California and later attended Santa Clara College in Massachusetts, is considered a pioneer of aviation and a precursor to the Wright brothers.

3. May 31, 1911 marked the opening of the Massachusetts Institute of Technology's (MIT) first campus in Cambridge, Massachusetts. Today, MIT is one of the world's leading research institutions and has produced numerous Nobel laureates and innovators in the fields of science, engineering, and technology.

4. On this day in 1961, civil rights activist and lawyer Robert F. Kennedy delivered a speech at the University of Massachusetts Amherst, where he called for greater racial integration and justice in America. Kennedy went on to become Attorney General under his brother President John F. Kennedy, and continued to advocate for civil rights until his assassination in 1968.

5. May 31, 2004 was the day that the first same-sex marriages were performed in Massachusetts, making it the first state in the United States to recognize them. This landmark decision came after the Massachusetts Supreme Judicial Court ruled that denying gay and lesbian couples the right to marry was unconstitutional.