As the Mormons moved westward across America in the winter of 1846-47 to escape religious persecution, about 20 families stopped in a place called Indiantown. They stayed there for several years.
Cass County was not organized until 1853 when the first commissioners met in Indiantown to fix the location of the original Cass County seat. Their choice was a site called Lewis, in honor of Lewis Cass, and a two-story house was used for court and county business.
The railroad passed through the city of Atlantic and this growing city offered a block of land for a courthouse in hopes of becoming the new county seat. Their offer was accepted in 1869 and a small frame building was constructed. It soon became inadequate and the county rented the Park House across the street for $1,200.
In 1888, a new two-story brick and stone building was built. In March 1932, a fire destroyed the courthouse, but the county records were saved. Salvaged materials, insurance money, and a federal grant were used to construct the present courthouse, which cost $119,000.
This brick building is trimmed with Indiana limestone and stands three stories high. It was dedicated in 1934.