Which treaty defined the southern boundary of the United States at the 31st parallel?

The Pinckney Treaty, also known as the Treaty of San Lorenzo, was established in 1795 between the United States and Spain. One of the key provisions of this treaty was the definition of the southern boundary of the United States at the 31st parallel. This treaty was significant because it resolved longstanding disputes over territory and trade, particularly concerning navigation rights on the Mississippi River. It allowed Americans to transport goods along the river and increased the security of American frontiers by clearly defining their boundary with Spanish territories. This context highlights the importance of the Pinckney Treaty in promoting peaceful relations and trade between the two nations during a time of expansion and uncertainty for the young United States.