Interstate 81 begins in at an interchange with Interstate 40 near Dandridge in Jefferson County. About later is an interchange with SR 341, which connects to SR 66 a short distance later, providing access to Morristown. later, I-81 crosses into Hamblen County and meets U.S. Route 25E south of Morristown. Continuing through mostly rural terrain, I-81 has an interchange with SR 160, the final Morristown exit, about later. About later, the interstate crosses over a ridge and into Greene County. About beyond this point is an interchange with US 11E, which provides access to Greeneville to the southeast and Bull's Gap to the northwest. Continuing through a predominantly rural and agricultural area, I-81 reaches SR 70, which connects to Greeneville to the south and Rogersville to the north. Beyond this point, the interstate remains in a predominantly rural and agricultural area, and begins a slight uphill climb, with the northbound lanes utilizing a truck climbing lane for about near the community of Jearoldstown, where the route also shifts slightly to the northeast. A few miles later, I-81 shifts sharply east and crosses into Washington County. Less than a mile later is an interchange with SR 93, which provides access to Jonesborough to the south and Fall Branch to the north. I-81 then turns northeast again, and about later enters Sullivan County. Entering a semi-urbanized part of the Tri-Cities area, I-81 connects to I-26 and US 23 in a cloverleaf interchange about later. This route provides access to Kingsport to the north and Johnson City to the south. A little over two miles later is an interchange with SR 36, another major connector between these two cities. I-81 then crosses the Holston River about a mile later, and begins another slight uphill climb, once again gaining a truck climbing lane on the northbound lanes. About later the truck lane terminates at an interchange with SR 357, a connector to the Tri-Cities Regional Airport, and the route continues through the semi urban area, briefly shifting eastward and crossing a ridge about later. Shifting northeastwardly again, I-81 has an interchange with SR 394 near the city ofBlountville. Beyond this exit, the route crosses a slight upgrade once again, before reaching a relatively flat stretch again. About later, I-81 reaches Bristol and widens to six lanes. The route then has a cloverleaf interchange with US 11W, before crossing into Virginia later.
History
One of the first sections to be opened to traffic was the segment between US 11W and the Virginia state line, opened by the early 1960s. The segment between the southern terminus with I-40 and US 25E in Hamblen County was completed in late 1966. Like most of the interstates in Tennessee, priority was generally given to completing sections in Middle and West Tennessee over East Tennessee, and as a result, most of I-81 in Tennessee was not constructed until after the late 1960s. The contracts for most sections of the route were awarded in 1969 and 1970. On December 20, 1974, two lanes of the final section in Tennessee, the section located between US 11E near Morristown and SR 126 near Blountville, were opened to traffic, and the section was completed on August 27, 1975.
Exit list
Auxiliary routes
in Johnson City and Kingsport is a former spur route that was renumbered as I-26 by March 2007.