Harrison County (Tex.)

Located in northeastern Texas along the Louisiana border, Harrison County was inhabited by Caddo Indians before the arrival of Spanish explorers in the 16th century. American settlers received the first Mexican land grants for the area in 1835. After the Texas Revolution, the population grew and the Congress of the Republic of Texas officially established Harrison County in 1839, naming it after Texas revolutionary leader Jonas Harrison. The town of Marshall was founded in 1841 and became the county seat one year later. Settled largely by Southerners who replicated their cotton-plantation society in Texas, Harrison County had the most slaves of any Texas county by 1850 and was also one of the most agriculturally productive.

Source:

...