A bit of Harrison County history:

American settlers began to arrive in large numbers during the 1830s. The settlement of the area was well under way by the time of the Texas Revolution in 1836. A dozen Americans received land grants there from Mexican authorities in the fall of 1835. After the revolution the area filled up so rapidly that the Congress of the Republic of Texas officially established Harrison County in 1839. It was drawn from Shelby County, organized in 1842, and named for Texas revolutionary leader Jonas Harrison. Marshall, founded in 1841, became the county seat in 1842. The original county boundaries were reduced by the establishment of Panola and Upshur counties in 1846. Since then, with the exception of a small adjustment with Marion County during Reconstruction, they have remained unchanged.