Buchanan Township contains an area of 17,813 acres. It is bounded on the East by Niles Township, on the South by Bertrand, on the West by Weesaw, and on the North by Oronoko and Berrien Townships. The Township contains little level land, the highest point is Moccasin Bluff. The soil is clay loam and a mixture of sand. The territory of the Township was partly included in a tribal reservation on which the Potawatomies lived during the later years of their residence in Berrien County. The first cession of land that affected this part of Berrien County was on September 20, 1828, which embraced the land lying west of the St. Joseph River, except the reservation. The Greater part of Buchanan Township is in the tract ceded in 1828, but the village is in the reservation. This ceded in 1838. The best land in the last cession was chosen by the Commissioners as seminary land, and most along McCoy Creek. The land was largely settled by those who intended to purchase the land, however, when a price of $20.00 an acre was put on the land they were compelled to give it up. Later the price was reduced to $12.00, later to $6.00.

The town derived its name from James Buchanan. At the time of organization there were about 27 families. The act by which it was erected, (approved March 11, 1837) provided "all that portion of the County of Berrien be so much of the township seven South of range eighteen West, as lies west of the St. Joseph River by, and the same hereby, set off and organized into a separate township by the name of Buchanan".

The first meeting was held April 7, 1837 in the home of the first supervisor C.C. Walen.

The first census was taken in 1840, population 264. The latest census in 2000 was 3,510.

In 1837 the first real estate assessment was $45,000.00, personal $1,377.00 for a total of $46,377.00.

The first School District #1 was organized May 12, 1838.

The first Primary School Money from the state amounted to $32.64.

In 1929 the Village and Township divided. The Township received an old typewriter and election booths.

The first Board after the separation was:

The meetings were held in homes. The elections were held in the Wagner Grange Hall.

In 1941 the Board voted to buy a fire truck. An agreement was made between the City and the Township that the Township would furnish a fire truck and it would be stationed at and manned by the City. In 1943 a 37 chassis and a general pumper were bought. In 1949 a new truck was purchased.

On May 16, 1952 land was purchased by the Township from Zoda Suit for $1,000.00 for one acre.

In 1954 the original hall and a fire truck stall were built.

In 2000 a new fire station was built.

In 2002 the Township offices were remodeled and expanded into the old fire bays at a cost of $148,875 with no increase in taxes.