In 1842 a group of German immigrants settled in Buchanan.  The Town of Buchanan was established in 1858.  The Holy Angels Catholic Church was erected in 1874 and is a key landmark in the town.

Darboy, as much of the town is commonly known, is an unincorporated community.  The Darboy name stems from a post office that was established in 1877 and named after French Archbishop Georges Darboy.  The post office closed in 1901. 

In 1972, local farmers concerned about future growth in Darboy, organized the Darboy Joint Sanitary District No. 1.  The District's water and sewer services helped fuel the explosive population growth in the 1990s.  The present Buchanan Town Hall was built in 1991.

In 2000 the town had a population of 5,827.  The town experienced 15% growth since 2000, resulting in a 2007 population of 6,719.