On 1 September 1814 the original boundary of Washington County was increased, by act of the Territorial legislature, but on 26 December 1815 much of this added territory was partitioned off to create Orange and Jackson counties. In December 1816 the Indiana Territory was admitted to the Union as a state. On 12 January 1820 the state partitioned a further portion of Washington County to create Scott County. In 1842, and again in 1873, the border between Scott and Washington counties was adjusted.