Skip to main content

This Day in American History

March 15

1 historic event on this date

Legislation1820

Maine Admitted as 23rd State

Maine was admitted to the Union as the 23rd state and a free state, as part of the Missouri Compromise. Maine had previously been part of Massachusetts, and its admission was paired with Missouri's entry as a slave state to maintain the balance of power in the Senate.

Why It Matters

Maine's admission demonstrated how the political balance between free and slave states shaped the nation's growth, and how legislative compromise could temporarily hold the Union together.

Explore the Principles Behind the History

Every event in American history connects to the founding principles. Discover the ideas that shaped these moments.

View the 28 Founding Principles