Tennessee State Route 75

State Route 75 (SR 75) is a state highway in Tennessee in the northeastern portion of the state. The highway begins at US 11E and US 321 in Limestone and ends at SR 126 in Blountville.

Washington County
SR 75 begins as a 2-lane highway in Washington County in Limestone at an intersection with US 11E/US 321/SR 34. The highway then heads northeast through rural farmland to have an intersection with SR 81 just before passing through Sulphur Springs. SR 75 then continues to enter Gray, where it has an interchange with I-26/US 23 (Exit 13). The highway then widens to a 4-lane undivided highway and passes just southeast of downtown before leaving Gray and passing through Spurgeon, where it has an intersection with SR 36. SR 75 then crosses the South Fork Holston River into Sullivan County, just north of Boone Dam and Boone Lake.

Sullivan County
SR 75 continues northeast to pass through Boring before entering Blountville and passing by the Tri-Cities Regional Airport, where it has an interchange with SR 357. SR 75 then narrows to 2-lanes and passes rural areas of Blountville before entering downtown, where it comes to an intersection with SR 126.

The entire route of SR 75 is a secondary highway.

History
The current SR 75 is the third state highway in Tennessee to bear this numbering. The first alignment was one of the original state highways established on October 1, 1923, and ran between Springfield to the Kentucky line along what is now US 31W. In 1925 or 1926, this route was truncated by part of SR 79, and completed renumbered as part of SR 49 and SR 52 in 1927 or 1928 Around the same time, the second SR 75 was established between the North Carolina line near the Sevier-Cocke County line and US 25/70 in Newport. This route was renumbered as part of SR 32 in 1939 or 1940. The present-day SR 75 was established between 1964 and 1969, as a renumbering of part of SR 37 between US 23 in Gray and SR 126 in Blountville. On July 1, 1983, SR 75 was extended south to US 11E/321 in Limestoneon Gray Station Road as part of a statewide takeover and renumbering of roads that year. Signs were posted the following year.

In May 2000, the Gray Fossil Site was discovered by TDOT construction crews along SR 75 near the Gray Community. This site consists of fossils from the early Pliocene era that are between 4.5 and 4.9 million years old. A museum on the site opened in 2007.

Future
A widening project has been taking place on SR 75 to provide a four-lane highway from Interstate 26 in Gray to the Tri-Cities Regional Airport in Blountville. On November 1, 2013, TDOT opened all four lanes of traffic, but much work still needs to be done.