Buchanan is a city in Berrien County in the U.S. state of Michigan. The population was 4,681 at the 2000 census. The city is located at the southeast corner of Buchanan Township, about 5 miles (8 km) west of Niles. Popularly known as "Redbud City" because of the many redbud trees that have historically lined city streets and the major approaches to the city, Buchanan has long been recognized as a Tree City USA by the National Arbor Day Foundation.