In 1909, this property was purchased by The Leinart Company composed of T.H. Leinart, J.O. Leinart, and R.E. Leinart. A smaller wooden post office building existed here prior to the big 1908 Market Street fire but was soon replaced with this iconic structure with its arches of colored brick and brownstone trimmings in 1909. After its construction, the post office occupied the first floor with offices on the top two floors. When the Clinton Library Association was organized in 1912, their reading room occupied the third floor.