The Unionville City Hall is located at 1611 Grant Street, Unionville MO 63565.
Unionville (originally called Harmony) was established in 1853 as the county seat of the newly established Putnam County. Putnam County was created by the consolidation of Dodge and Putnam counties, both reduced by the loss of their northernmost 12 sections to neighboring Iowa in 1851. Neither of the county remnants was large enough to constitute a county so the two were joined in a single, elongated 36x14 mile configuration. Unionville was the name imposed by the Legislature on February 5, 1855 because there was another Harmony in the state. Incorporation followed on November 4, 1857.