US 76 Laurens to Greenville; SC 284 to Caesars Head 1930 Official

US 276 appears 1933 Official

Adjustments: In 1938, US 276/SC 2 was placed on newly constructed route on the east side of the railroad from Barksdale through Gray Court and Owings to Fountain Inn area. The old route became secondary except right in Gray Court was a primary route with unknown designation (probably an ALT route of SC 2 or SC 101) plus a little of SC 101 itself. Today the old route is the very lengthy Old Laurens Rd which is mostly not in the secondary system but is S-30-414 on the northernmost couple miles; SC 101 and S-30-13 Main St in Gray Court.

US 276/SC 2 west of Railroad through Gray Court and Owings 1937 Official

US 276/SC 2 east of Railroad through Gray Court and Owings 1938 Official

In 1947, SC 2 was dropped from US 276.
Also by 1947, US 276 was moved onto Stone St around the north of downtown Greenville. Some of this was primary in 1940 but not known what the designation was. The old route via North, Buncombe, and Rutherford Sts became US 276 Business (now I-385 Business, a bit of SC 183, and S-23-200).
In 1958, US 276 was placed on newly constructed freeway bypassing Simpsonville and Fountain Inn. Mauldin to Fountain Inn became US 276/SC 14 CONN (now SC 417) and the rest became part of SC 14.
In 1959, US 276 was placed on new expressway routing in the Furman University area, leaving behind more S-23-13, plus S-23-2 which is now the ramp from S-23-13 to US 276 south.

US 276 original Furman area routing 1957 Greenville County

US 276 on new expressway 1963 Greenville County

In 1960, US 276 was placed on more new freeway southeast to the new I-26 near Clinton, with the old route to Laurens becoming more SC 14.
In 1983 (AASHTO), US 276 was added to new freeway construction connecting the US 276 freeway in Mauldin to the I-85/385 jct, with US 276 continuing into Greenville with I-385. The old route through Mauldin to the last exit on I-385 in downtown Greenville became US 276 Business.
In 1984 (AASHTO), US 276 was removed from I-385 in Greenville and placed back on its route through Mauldin to Downtown Greenville. Also, US 276 from Mauldin southeast to I-26 became an extended I-385.

SC 14 extended to Fountain Inn 1958 Official

SC 14 extended to Laurens 1960 Official

US 276 truncated to Mauldin 1986 Official

Improvements: Fully paved upon designation.
The first multilane section of US 276 was SC 146 to Mauldin, in 1957.
In 1958, US 276 was multilaned on the new construction from Mauldin to Fountain Inn.
The next section to be upgraded was Furman University to Travelers Rest in 1959.
In 1960, US 276 was multilaned when moved onto its new expressway from Fountain Inn to I-26.
In 1962, US 276 was 4-laned on all its US 25 multiplex
In 1971, US 276 was 4-laned from SC 146 west to I-385.
In 1974, US 276 was 4-laned through the rest of Downtown Greenville.
In 1982, US 276 was 4-laned from Travelers Rest to Marietta.
Comment: US 276 provides the best opportunity for serious mountain driving within South Carolina on a decent surface, as from SC 8 northward it is pretty twisty.
With the extension of I-385 the importance of US 276 has declined seriously in South Carolina. I have my doubts that the brief existence of US 276 on I-385 from Mauldin to Greenville was posted as such...