TN 42 Three Way-Greenfield-Dresden 1924 Official

TN 42 renumbered as TN 43 and TN 54 1929 Official

TN 42 #2: Appeared in 1927 or 1928 as a renumbering of TN 74, running from TN 26 (now S. Maple Ave) Crossville to US 70 Crossville.
In 1931 or 1932, TN 42 was renumbered as part of TN 24 in a route swap. Today it is US 70N except: E. Hudgens St out of Crossville (now cutoff by TN 111); the west half of Parker Rd north of I-40; some of I-40's footprint at Exit 300 and 1/4 mile west; a touch of Industrial Rd north of I-40;
The 1929 and 1930 Officials suggest the route crossed the railroad multiple times but there doesn't seem to be any roads even on older topos that do this except Junior Camp Rd west of Mayland...the 1932 Official does not show it, so it is possible TN 42 was placed on the modern route before becoming TN 24.

TN 74 Algood to Crossville 1924 Official

TN 74 becomes TN 42 1929 Official

TN 42 #3: Appeared in 1931 or 1932 as a renumbering of TN 26 from US 70 Sparta to Cookeville and a renumbering of TN 24 from Cookeville to the Kentucky line at Static.
In 1935, TN 42 was removed from Old Sparta Rd (no longer reconnects in White County) south of Cookeville; S. Maple Ave and Whitson Ave (used to connect south of Stevens St), plus Proffitt and S Washington Ave all within Cookeville.
In 1939 or 1940, TN 42 north was truncated a tiny, tiny distance and instead TN 28 went to the state line instead.
In 1942, TN 42 was removed from the substantial Old Cookeville Rd north of Sparta, Old Kentucky Rd, S. Cookeville Lane and Leon Luke Rd (both ends of this are cutoff by the TN 111 freeway today).
In the mid-40s, TN 42 was rerouted to a new Obey River crossing (slightly west of current TN 111's crossing) to accommodate Dale Hollow Lake. The original crossing used Dale Hollow Estates Rd which used to go more directly west across Obey Park Rd and 3/4 mile to the original bridge which was very close to the small island in the river, then connected east to the end of Palnk Yard Rd then Lakeview Heights Rd.
The one-way splits in Livingston using Broad St WB and Main St EB (original TN 42) may have been in place as early as the mid-1950s
Between 1961-64, TN 42 was removed from Old Highway 42, Dale Hollow Estates Rd (no longer connects to) and Obey Park Rd south of the Obey River.
In 1965, TN 42 was removed from Twin Oaks Rd and Big Springs Rd north of Livingston. This may also have been when TN 42 was removed from Beaty Swamp Rd/Old Livingston Rd
In 1975, TN 42 south was truncated to Cookeville as it was replaced by the TN 136 south out of Cookeville, then TN 111 to Sparta. Today this is TN 136, Roberts-Matthews Hwy (except it used Paul Gordon Rd at south end) and TN 289.

TN 42 from Sparta to Kentucky line 1932 Official

TN 42 south truncated to Cookeville 1986 Official

Between 1975-81, TN 42 was given a bypass of Livingston, leaving behind TN 85 through town plus today's TN 294 (unsure if this had a state highway designation before 1983).
Also by 1979, TN 42 was given a bypass of Byrdstown, leaving behind today's TN 325 and N. Main St.
In 1980 (bridge date), the north end of the original TN 111 bypass of Cookeville was extended as new construction around Algood to TN 42 (now E. Main St). It is unclear whether TN 42 was placed on this or whether TN 111 transitioned to TN 42 at the end of the Cookesville bypass. It does appear TN 42 was removed from Cookeville entirely leaving behind N Washington Ave and E 10th St.
In 1988, TN 42 was removed from the lengthy Old SR 42/Main St from north of Algood through Rickman and Kalona up to the south edge of Livingston.
Also in 1988, TN 42 was rebuilt between Byrdstown and US 127, leaving behind Old Static Rd (no longer connects to)/Red Hill Rd
Between 1990-92, TN 42 from Cookeville/Algood to US 127 became part of TN 111. It remains so today except TN 42 was still using Obey Park Rd off TN 111 to removed bridge over the Obey River; abandoned wavy routing to the north that connected to the end of Lakeview Heights Rd; Old piece of TN 111 right at US 127.

TN 42 truncated to Algood Bypasses for Livingston and Byrdstown 1986 Official

TN 42 bypasses Rickman and straightened out 1989 Official

TN 111 replaces the rest of TN 42 1993 Official