Caribou is the second largest city in Aroostook County, Maine, United States. Its population was 8,189 at the 2010 census.
In 1807, Charles Turner surveyed ten thousand acres (40 km²) of land in northern Maine, then part of the state of Massachusetts. In 1808, Captain William Eaton was deeded these same 10,000 acres (40 km²) as a reward for his heroic victory over the Barbary Pirates. This estate became known as the Eaton Grant, and now comprises the southeastern section of Caribou. Around 1824, settlers began arriving from New Brunswick and settled on the north side of the Aroostook River.
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. Caribou became the largest potato shipping hub in the world, and had many related industries. Loring Air Force Base opened in the neighboring town of Limestone in the early 1950s, and this also provided a major boost to Caribou's growth. Caribou was incorporated as a city February 23, 1967. Its population began to slowly decline thereafter, a result of difficulties in its traditional potato industry. The 1994 closure of nearby Loring Air Force Base also contributed to the decline in Caribou's population, as the city had served as the main service center for the base's 8,000 residents. In more recent years, Caribou's population has stabilized and grown slightly as the city successfully adapted to the base's closure and its economic impact.