National Maine Day is observed worldwide every December 21, recognizing Maine as the 23rd state to join the Union. Established in 2017 by National Day Calendar, this unofficial holiday celebrates Maine's rich history and cultural significance. The state, known as the "Pine Tree State" and "Vacationland," is characterized by its abundant white pine forests and natural beauty, making it a popular summer getaway. The origins of the name "Maine" date back to 1622, although its exact source remains unclear. Historically, Maine was home to the Algonquian-speaking Wabanaki peoples before European exploration began with figures like John Cabot and Giovanni da Verrazzano in the late 15th and early 16th centuries. The state became part of the Massachusetts Bay Colony in the late 1600s and officially separated to join the Union in 1820. National Maine Day is part of the National State Days project, which celebrates states in the order of their admission.