Kidder is a city in Caldwell County, Missouri, United States. The population was 271 at the 2000 census. The city was laid out in 1860 by H.B. Kidder of the Kidder Land Company in Boston, which was seeking to encourage non-slave owning European immigrants to settle along the Hannibal and St. Joseph Railroad which at the time was the furthest west railroad in the United States. The city received national publicity in 2004 after a student at the Thayer Learning Center in the community died after not receiving treatment early enough. In 2009 the Center was sold to become the White Buffalo Academy. The campus was formerly Thayer College and Thayer High School. Thayer College was founded in 1871 and closed in 1876. It reopened in 1877 as the Kidder Institute and operated under the auspices of the Congregational Church of Missouri. The building was used as a public school from 1934 to 1981.