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Simpson County: Triangular Jog

Historical account by Tim Talbott, based on the "Triangular Jog" marker #1850 located in Simpson County, Ky. Accompanying photos, marker location, and more can be found here. 

Triangular Jog
Marker Number: 1850
Location: Ky.-Tenn. State Line, US 31-W South
The Simpson County jog in Kentucky-Tennessee boundary was error of Dr. Thomas Walker's 1780 survey party. Luke Munsell and James Bright resurveyed region fifty years later, but the controversy continued until survey by Austin P. Cox and Benjamin Peebles in 1858-1859. This stone-marked line set official boundary between the two states and ended an 80-yr. dispute.
 
Historical Marker #1850 in Simpson County notes the irregular boundary protrusion that occurs on the Kentucky-Tennessee state line where Interstate 65 crosses the border.
 
Looking at almost any map of the United States, it is easy to see the unusual boundaries between some of the states. Some state lines are determined by geographical features, such as Kentucky’s northern border of the Ohio River. Other boundaries are surveyed and appear quite uniform until, upon closer examination, some irregularities are found.

One such irregularity is located on Kentucky’s southern border, where Simpson County dips triangularly southward into Robertson and Sumner Counties in Tennessee. This abnormal offset occurred when surveyors, using imperfect astronomical measurements in 1780, were unable to maintain a straight bearing due to weather conditions. In addition, it is believed that their calculations were further altered by the large iron ore deposits, which distorted their surveying compass readings.

Simpson

County Map of Kentucky and Tennessee, 1894, KHS Map Collection, Accession No. 976.03 S642

The irregular boundary was kept intact until a dispute arose, and the line was resurveyed in the 1830s. It became obvious that if the original line were moved, it would create difficult issues of state citizenship for those living in the area in contention. Another survey was conducted in 1859, which determined that about 100 acres of property belonging to a Sumner County, Tennessee, citizen named Middleton was actually in Kentucky. The surveyors determined that this man’s property should remain in Tennessee. Within the triangular offset, a rectangular offset protruded northeastward.

Today, with modern technology tools such as Global Positioning Systems, the “Simpson County Offset” would not occur. Yet, working with the equipment eighteenth-century surveyors used, it is surprising that many more such errors did not occur.

This story, along with many others, can be found at ExploreKYHistory.ky.gov. KHS invites you to explore Kentucky history online and on the road with the ExploreKYHistory smartphone app. ExploreKYHistory takes the stories behind our community-driven historical markers, adds related items from the KHS collections, and combines them into a historical tour of our Commonwealth.

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