1. First US Missionary Society Established in Vermont: On September 3, 1801, the first American Missionary Society was established in Hartford, Vermont. The society aimed to spread Christianity and built religious schools and churches across the United States.

2. Vermont Celebrates Bennington Battle Day: September 3 is a state holiday in Vermont which commemorates the victory of the Revolutionary War Battle of Bennington. It took place on August 16, 1777, in the town of Old Bennington, which is now modern-day Vermont.

3. Vermont Becomes the 14th State: On September 3, 1791, Vermont became the 14th state to join the Union. Before Vermont, the last state to join was Rhode Island in 1790.

4. Vermont's First African-American Legislator Elected: Alexander Twilight was elected to the Vermont House of Representatives on September 3, 1836. He was Vermont's first African-American legislator and among the first in the U.S.

5. Vermont Hosts the First Abolitionist Convention in the US: On September 3, 1834, the first anti-slavery convention in the U.S. took place in Putney, Vermont. The convention was held to discuss the abolition of slavery and was attended by notable figures like William Lloyd Garrison and Henry C. Wright.