On October 27, 1795, the United States concluded the Treaty of San Lorenzo with Spain, establishing 31 north latitude as the boundary between its southern territory and West Florida. Despite Spanish delays, commissions representing the two countries began the eastward survey at the Mississippi River. They passed this point in August 1799, and continued to the Chattahoochee River. They later abandoned the boundary survey east of the river due to persistent Indian attacks. The 381 mile survey became known as Ellicott's line in reference to Andrew Ellicott, surveyor for the U.S. commission.