TN 66 Tazewell to Rogersville via Sneedsville 1924 Official

TN 66 south extended to Bulls Gap 1929 Official

TN 66 truncated to Sneedsville area 1940 Official

Between 1944-46, TN 66 south was extended with US 11E to Morristown, then with US 25E to White Pine, then southwest as new state highwy to US 25W-70, then with those routes to Dandridge, then southwest as more new routing to end at TN 35-71 (now US 411-441) Sevierville.
In 1952 or 1953, TN 66 was rerouted at Morristown to head directly to Dandridgeas new primary routing, The road from White Pine to US 25W-70 became TN 66A (now TN 113).
In 1958, TN 66 was rerouted west of McCloud to its current crossing of the Holston River as new construction. The old crossing was directly north of where today's Old Hwy 70 crosses the railroad about a mile east of current TN 66-70. TN 66 was also removed from a mile of McKinney Chapel Rd on the north side of the river as well as Big Springs Rd through Henardtown.
About 1966, TN 66 was given its bypass of Rogersville leaving behind Broadway/Depot/Main St.
Also about 1966, TN 66 was removed from Daisy St/E. Main St/Mornigside Dr and placed on E. 1st North St east out of Morristown
About 1967, TN 66 was puy on its modern routing south of the Holston River. The 1958 bridge included a stub that extended a short distance (see second topo scan below) which was extendd further as newly constructed routing. The old routimg became Old TN 70, a rerouted TN 70 (now Old Persia Rd), and Old TN 66.

TN 70 original route west of McCloud 1940 Topo

TN 70 moved to new Holston River bridge 1964-65 Topos

TN 66 rerouted away from Chalk Level and Persia 1969 Hawkins County

About 1975, TN 66 was rerouted to run Sevierville north to I-40 as mostly new construction, then implied concurrencies with I-40 east to US 25W-70 east back to Dandridge. The old route became Douglas Dam Rd (now TN 338 and TN 139) plus a couple blocks of TN 92.

TN 66 extended south to Sevierville 1948 Official

TN 66 removed from US 25E 1956 Gousha

TN 66 rerouted to I-40 1981 Official

Between 1982-85, TN 66 was moved to use Morris Blvd and a bit of US 25E through Morristown.

TN 66 original Morristown route 1962 Hamblen County

TN 66 on 1st St all the way 1980(?) Hamblen County

TN 66 moved to Morris Blvd 1985 Hamblen County

In 1995 or 1996, TN 66 was placed on TN 160 and newly constructed ML King Pkwy south of Morristown. This left behind Valley Home Rd.
In 2008, TN 66 was removed from Jarnigan Ave and placed on newly built extension of ML King Pkwy
In late 2020, TN 66 was placed on new multilane routing from TN 341 to TN 160, then replaced TN 474 to US 11E Morristown then east with US 11E to pickup where old 66 ran. The old route became 3 discontinuous segments of Valley Home Rd plus ML King Pkwy in Morristown
Posting: Posted as secondary from Dandridge to TN 341 and from Rogersville to TN 33; posted as primary everywhere else except its overlays with I-40, US 25W-70, and US 11E are unposted.
Secret US Route Overlay: none
Comment: TN 66 is the major corridor from both Sevierville and Morristown to I-40.
TN 66 is little changed on its rather arduous routing north of Rogersville.