Between 1838 and 1839, the undeclared Aroostook War flared between the United States and Canada, and the Battle of Caribou occurred in December 1838. The dispute over the international boundary delayed settlement of the area until after the signing of the Webster-Ashburton Treaty in 1842. With peace restored, European settlers arrived in large numbers in 1843. From Eaton Plantation and part of half-township H, Caribou was incorporated on April 5, 1859, as the town of Lyndon. In 1869, it annexed Eaton, Sheridan and Forestville plantations. On February 26 of that year its name was changed to Caribou, only to revert back to Lyndon on March 9. On February 8, 1877, Caribou was finally confirmed as the town's permanent name. Two enduring mysteries are the reason for the original name of Lyndon, and the reasons for the town's name being subsequently changed back and forth between Lyndon and Caribou. The small town grew throghout the late 19th century, and with the coming of the Bangor and Aroostook Railroad in the 1890s, agricultural exports exploded. This began a boom period which lasted well into the 1960s.
