It was placed on April 10, 1799, by a joint U.S.-Spanish survey party headed by Andrew Ellicott.

[1][5] It is the only known stone monument set by Ellicott when he surveyed the 31st parallel north latitude, which served as the boundary line between the Mississippi Territory in the United States and Spanish West Florida.

[6][7] Ellicott's Stone is the initial point for all United States Public Land surveys in the southern region of Alabama and Mississippi.

[5] It is now near the James M. Barry Electric Generating Plant, west of the Mobile River.

[8] The stone marker, a ferruginous sandstone block about two feet high and eight inches (203 mm) thick, is near the west bank of the Mobile River.