NEUTRAL GROUND. After the Louisiana Purchase, the United States and Spain were unable to agree on the boundary between Louisiana and Texas. In order to avert an armed clash, Gen. James Wilkinson and Lt. Col. Simón de Herrera,qqv the American and Spanish military commanders respectively, on November 5, 1806, entered into an agreement declaring the disputed territory Neutral Ground. The boundaries of the Neutral Ground were never officially described beyond a general statement that the Arroyo Hondo on the east and the Sabine River on the west were to serve as boundaries. It may be safely assumed, however, that the Gulf of Mexico constituted the Southern boundary and the thirty-second parallel of latitude formed the northern boundary. Although it had been stipulated in the agreement that no settlers would be permitted in the Neutral Ground, settlers from both Spanish and American territory moved in. The two governments were compelled to send joint military expeditions in 1810 and 1812 to expel outlaws who were making travel and trade in the neutral strip dangerous and unprofitable. Ownership of the strip went to United States by the Adams-Onís Treaty in 1821.
J. V. Haggard, "The Neutral Ground between Louisiana and Texas, 1806–1821," Louisiana Historical Quarterly 28 (October 1945).