Ellicott Southern Boundary

The Cornerstone of Alabama History

Inducted in 1999

On May 4, 1796, President George Washington commissioned Major Andrew Ellicott to survey the boundary line between the United States and the Spanish colonies of East and West Florida extending from the Mississippi River to the Atlantic Ocean. Until that time the southern portion of what is now Alabama, later known as the Mississippi Territory, had been claimed by Spain. This changed on October 27,1795, upon the signing of the Pinckney Treaty at San Lorenzo.

The running of the survey line for the first southern boundary of the United States began on the east bank of the Mississippi River in May of 1798. By March of 1799, the boundary commissions of the U.S. and Spain arrived in what is now Alabama. Major Ellicott, an army officer, distinguished astronomer, mathematician, and surveyor, sailed his schooner, Sally, up the Mobile River and established an astronomical observatory on Seymour’s Bluff, about 24 miles north of the city of Mobile on the west bank of the river.

Over the course of 21 days, Ellicott made six observations on each of four stars to establish a control point for his compass line that ran east to west, parallel to the 31st degree of north latitude. His observations ended on April 9, with the results being that his compass line was 8,556 feet north of the 31st parallel. After carefully laying out corrections to the south, the commissions of the U.S. and Spain set up a two and one-half foot high sandstone marker. This rock, known today as Ellicott’s Stone, serves as the point of origin for all land surveys in South Alabama and Southeast Mississippi.

In surveying this line of demarcation between the U.S. and Spanish West Florida, Ellicott built two more astronomical observatories in Alabama: one on the banks of the Conecuh River near present-day Flomaton and the other on the west bank of the Chattahoochee River northeast of Chattahoochee State Park. Ellicott marked the boundary line by having his men build a mound at each mile on the final or corrected line. Today approximately 200 of these mound sites, commissioned by President George Washington to mark the first U.S. southern boundary in what is now Alabama, await identification and preservation. This important task takes on even greater significance when one considers that these unidentified or obliterated mound sites, according to both the Alabama and Florida legal codes, establish the legal description of the boundary line between the two states.

In 1968, the boundary that Ellicott’s Stone marks was chosen as one of the first 10 American Society of Civil Engineers Historic Engineering Landmarks. This places the old boundary line in the same company as the Hoover Dam and the Brooklyn Bridge. The stone is also on the National Register of Historic Places and is con-sidered to be the oldest aboveground structure in Alabama. This April will witness the completion of a pavilion park to increase access and to protect this “cornerstone of Alabama history.”

It is appropriate that in the year that marks the 200th anniversary of Alabama’s first U.S. survey and the bicentennial of the planting of the American flag on Alabama soil, Ellicott’s southern boundary, President George Washington’s legacy to our beloved state, is inducted into the State of Alabama Engineering Hall of Fame.

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