The Treaty of San Lorenzo, also known as Pickney’s Treaty was signed in San Lorenzo de El Escorial, Spain on this date. It was later ratified in the United States on March 7, 1796, and officially proclaimed by both countries on August 3, 1796. The treaty defined borders between Spanish and American territories and also granted the United States navigation rights to the Mississippi River. Spain had acquired Florida from Great Britain in the Treaty of Peace ending the American Revolutionary War beginning an almost 40 year period of rule known as the Second Spanish Period.  A joint American and Spanish survey team set the northern boundary of Florida at 31 degrees north latitude starting from the Mississippi River moving east to the St. Marys River, out to the Atlantic. The treaty strengthened the American presence in the southeast, and although it helped to settle some early boundary disputes, Spain and the United States continued to argue over boundaries until the U.S. acquired the Florida territories in 1821.