Ellsworth County was organized in 1867, and was named after Fort Ellsworth, a military post built on the bank of the Smoky Hill, in 1864. This fort was so called by General Curtis, in honor of the officer who constructed it, Allen Ellsworth, Second Lieutenant of Company H, Seventh Iowa Cavalry. When the name was adopted for the county it was supposed that the fort had been named in honor of Colonel E. E. Ellsworth of national fame. Ellsworth county seat is Ellsworth.