Even today, Mainers and Bay Staters don’t always see eye to eye. The seeds of their rivalry were planted in the late 1640s, when Maine was absorbed into the more populous colony of Massachusetts. Changing demographics put this merger to the test. Following the American Revolution, an influx of new settlers came pouring into the District of Maine. These transplants tended to vote Democratic-Republican while their counterparts down in present-day Massachusetts were mostly Federalists. A rift soon emerged between the state government in Boston and the Mainers under its protection.
The War of 1812 deepened the divide. In July 1814, the Royal Navy captured Eastport, Maine. And that was just the beginning: Within a few short weeks, all of eastern Maine found itself under British occupation. Massachusetts Governor Caleb Strong then made the controversial decision to withhold military relief. Due to an international boundary dispute over Moose Island and surrounding areas, the British continued to occupy eastern Maine until 1818—three years after the war ended. The following summer, Mainers voted to secede from Massachusetts. As a condition of the Missouri Compromise, the free state of Maine was admitted to the Union on March 15, 1820.