1. In 1846, the Maine State Legislature voted to establish the University of Maine in Orono. Today, it is the flagship campus of the University of Maine System and serves over 11,000 students.

2. September 21, 1921 marked the opening of the Maine State building at the Eastern States Exposition in Springfield, Massachusetts. The building showcased Maine's industry and resources, and was a popular attraction at the annual fair for many years.

3. On September 21, 1941, the USS Squalus submarine sunk off the coast of Portsmouth, New Hampshire during a training exercise. The crew was trapped inside for three days before being rescued, thanks in part to the efforts of a diving bell developed by a Maine company.

4. The first-ever Maine Greek Festival was held on September 21, 2002 in Portland. The festival celebrates the state's Greek community with traditional music, dance, and food.

5. In 2016, the Maine Supreme Judicial Court ruled on September 21 that a state law requiring female voters to register with their husband's surname was unconstitutional. The case was brought by a woman who had been denied the right to vote under the law because she had registered using her maiden name.