Pickneys treaty in 1795 firmly defined the northern border of florida. why was this necessary ?

The Treaty of Friendship, Limits, and Navigation Between Spain and the United States, signed in San Lorenzo de El Escorial on October 27, 1795, was necessary because it would become in an important diplomatic success for the United States.  It resolved territorial disputes between SPAIN and the USA; in addition, It gave American ships the possibility of free navigation on the southern portion of the Mississippi and the free passage through the port of New Orleans, then under Spanish control.