Question: Mustoe, Highland County, Virginia is situated along what highway that extends for 680 mi?

Context paragraphs:
Patna, Virginia: Patna is an unincorporated community in Highland County, Virginia, United States.  Patna is located 12.6 mi south-southeast of Monterey, Virginia on State Route 614.  The community is situated along the Cowpasture River in the southern section of the Cowpasture Valley of Highland County.

Trimble, Virginia: Trimble is an unincorporated community in Highland County, Virginia, United States.  Trimble is located 7.7 mi south of Monterey, Virginia.  The community is situated along the Dry Branch, a tributary of the Jackson River, near a gap in Little Mountain through which the Dry Branch flows.

Highland County, Virginia: Highland County is a county located in the Commonwealth of Virginia.  As of the 2010 census, the population was 2,321, in 2015, the population was estimated at 2,214.  Its county seat is Monterey.  Known as "Virginia's Switzerland" or "Virginia's Little Switzerland", Highland County is the least populous county in Virginia.  Highland lays claim to being one of the least populous counties and one of the highest average elevations east of the Mississippi River.

Palo Alto, Virginia: Palo Alto is an unincorporated community in Highland County, Virginia, United States.  Palo Alto is located 11.4 mi east-northeast of Monterey, Virginia on the South Fork South Branch Potomac River.  The confluence of Spring Run with the South Fork South Branch Potomac River occurs near the community and Highland County's border with Pendleton County, West Virginia is located less than 1/2 mi north of Palo Alto.

Mustoe, Highland County, Virginia: Mustoe (also Pinckney) is an unincorporated community in Highland County, Virginia, United States.  Mustoe is located 6.9 mi south-southwest of Monterey, Virginia.  The community is situated along U.S. Route 220 on the banks of the Jackson River.  According to the National Weather Service, the only tornado on record in Highland County occurred near Mustoe in 1959.

Bolar, Virginia: Bolar is an unincorporated community in Bath County and Highland County, Virginia, United States.  The community is located approximately 14.5 mi southwest of Monterey, Virginia and 13.4 mi northeast of Warm Springs, Virginia.  Bolar is situated along Bolar Run on Big Valley Road, which roughly follows the county line through the community.

U.S. Route 220: U.S. Route 220 (US 220) is a north–south U.S. Route in the eastern United States.  The highway extends for 680 mi from an intersection with US 1 in Rockingham, North Carolina, to its interchange with New York State Route 17 (NY 17; future Interstate 86 or I-86) in South Waverly, Pennsylvania.  Some sections of the route are part of the Appalachian Development Highway System's Corridor O as well as I-73 in North Carolina.  US 220 is a spur route of US 20; however, the two routes do not intersect nor do they connect via other spurs of US 20.

Clover Creek, Virginia: Clover Creek (formerly Clovercreek or McClungs Mill) is an unincorporated community in Highland County, Virginia, United States.  Clover Creek is located 10 mi south-southeast of Monterey, Virginia on State Route 678.  The community is situated in the Bullpasture Valley along the path of the Bullpasture River.  Beginning in 1897 with a decision by the United States Board on Geographic Names, the community was officially referred to as the single-word "Clovercreek"; however, in 1970, the board modified the community's name to the current two-word "Clover Creek".  During the French and Indian War, a British fort named Fort George was built near Clover Creek in 1754 consisting of a wooden stockade 90 ft square.  The fort was never directly attacked, though arrows were at one point launched against the fort from a distance leaving no damage.  George Washington may have visited the fort while traveling in the area, marking the only time Washington visited the region which is now known as Highland County.

Hardscrabble, Virginia: Hardscrabble is an unincorporated community in Highland County, Virginia, United States.  Hardscabble is located 10.3 mi north of Monterey, Virginia near the border with West Virginia.  The community is situated along the Straight Fork in the Alleghany Valley.

Vanderpool, Virginia: Vanderpool (also Galltown, Gaul Town, or Woodsborough) is an unincorporated community in Highland County, Virginia, United States.  Vanderpool is located 3.8 mi south-southwest of Monterey, Virginia at the junction of Virginia State Route 84 and U.S. Route 220.  The community is situated near Vanderpool Gap, through which the Jackson River flows.  Before the creation of Highland County in 1847, Vanderpool was proposed to be the new county's seat, though it was defeated in favor of Monterey.  Vanderpool was named after the Dutch explorer John Vanderpool, who was the first man to pass through the area on horseback and discovered the Vanderpool Gap.

Supporting paragraphs: Mustoe, Highland County, Virginia U.S. Route 220
Answer: U.S. Route 220