Question: What stretches about 1200 miles and borders the Blue Ridge Mountains?

Context paragraphs:
Mountain Masochist Trail Run: The Mountain Masochist Trail Run (MMTR50) is a 50 mi ultramarathon that winds its way through the Blue Ridge Mountains.  The course begins at the James River Visitor Center; runners cover a short out-and-back section on the Blue Ridge Parkway before completing a few short miles of road.  The course then meanders northward over various dirt and gravel roads in the National Forest before runners have to negotiate the second half of the course.  Leaving Long Mountain aid station, the second half includes dirt and old logging roads as well as several miles of single-track trail.  Many say the race is just beginning when you leave Long Mountain.  Upon reaching the last aid station at Porters Ridge, runners course downhill for 2.9 miles toward the finish in Montebello.  The entire MMTR course traverses some of the most beautiful areas in the Blue Ridge right around peak fall foliage.  The elevation climbs 9,200 feet and descends 7,000 feet.

Great Appalachian Valley: The Great Valley, also called the Great Appalachian Valley or Great Valley Region, is one of the major landform features of eastern North America.  It is a gigantic trough—a chain of valley lowlands—and the central feature of the Appalachian Mountain system.  The trough stretches about 1200 mi from Quebec to Alabama and has been an important north-south route of travel since prehistoric times.

Blue Ridge Mountains: The Blue Ridge Mountains are a physiographic province of the larger Appalachian Mountains range.  This province consists of northern and southern physiographic regions, which divide near the Roanoke River gap.  The mountain range is located in the eastern United States, starting at its southernmost portion in Georgia, then ending northward in Pennsylvania.  To the west of the Blue Ridge, between it and the bulk of the Appalachians, lies the Great Appalachian Valley, bordered on the west by the Ridge and Valley province of the Appalachian range.

James River Gorge: The James River Gorge is a water gap created by the James River in Central Virginia.  The Gorge is 2433 ft deep as measured from Highcock Knob 3073 ft to the James River 640 ft and is approximately 9.3 mi long.  The James River forms in western Virginia near the border of West Virginia and initially flows south through the ridge and valley province of the Allegheny Mountains, turning northeast when it comes to the western edge of the Blue Ridge Mountains near Buchanan, Virginia.  From Buchanan the river flows along the base of the Blue Ridge Mountains until it joins the Maury River near the town of Glasgow, Virginia and then it turns southeast and begins its descent over the Balcony Falls rapids and through the James River Gorge.  The rocks of the gorge are metamorphic in nature with the oldest exposed outcrops being from the Proterozoic Era.

USS Blue Ridge (LCC-19): USS "Blue Ridge" (LCC-19) is the lead ship of the two "Blue Ridge"–class command ships of the United States Navy, and is the command ship of the United States Seventh Fleet.  Her primary role is to provide command, control, communications, computers, and intelligence (C4I) support to the commander and staff of the United States Seventh Fleet.  She is currently forward-deployed to U.S. Navy Fleet Activities, Yokosuka in Japan, and is the third Navy ship named after the Blue Ridge Mountains, a range of mountains in the Appalachian Mountains of the eastern United States.  "Blue Ridge" is the oldest deployable warship of the U.S. Navy, following the decommissioning of  in Pearl Harbor on 14 August 2014.  "Blue Ridge", now the U.S. Navy's active commissioned ship having the longest total period as active, flies the First Navy Jack.  "Blue Ridge" is expected to remain in service until 2039.

Blue Ridge Mountains Council: The Blue Ridge Mountains Council is a Boy Scouts of America council located in Roanoke, Virginia that serves Scouts in southwest and south central Virginia.  The Blue Ridge Mountains Council owns and operates the Blue Ridge Scout Reservation in Pulaski County, Virginia.  The local Order of the Arrow lodge is the Tutelo Lodge.

Blue Ridge Music Center: The Blue Ridge Music Center is a music venue, museum, and visitor center located at milepost 213 on the Blue Ridge Parkway near Galax, Virginia.  The center celebrates the music and musicians of the Blue Ridge Mountains through concerts, exhibits, and programs that highlight living musical heritage of the Blue Ridge region and interpret its significance within the larger landscape of American music and culture.  The site is operated through a partnership between the National Park Service and Blue Ridge Parkway Foundation.  The Music Center operates May through October.  Free Midday Mountain Music acoustic sessions featuring local musicians are offered from noon to 4 p.m. daily.  Concerts are offered most Saturdays during the season and include old-time, bluegrass, folk, Americana, gospel, and country blues performances.  The Roots of American Music Museum on site showcases the region's rich musical heritage.  Admission to the museum is free.

Blue Ridge Tunnel: The Blue Ridge Tunnel (also known as the Crozet Tunnel) is a historic railroad tunnel built during the construction of the Blue Ridge Railroad in the 1850s.  The tunnel was the westernmost and longest of four tunnels engineered by Claudius Crozet to cross the Blue Ridge Mountains at Rockfish Gap in central Virginia.  At 4237 ft in length, the tunnel was the longest tunnel in the United States at the time of its completion in 1858.  The tunnel was used by the Virginia Central Railroad from its opening to 1868, when the line was reorganized as the Chesapeake and Ohio Railroad (renamed Chesapeake and Ohio Railway in 1878).  The Chesapeake and Ohio routed trains through the tunnel until it was abandoned and replaced by a new tunnel in 1944.  The new tunnel was named the "Blue Ridge Tunnel" as well, although the original tunnel still remains abandoned nearby.  The old Blue Ridge Tunnel has since been named a Historic Civil Engineering Landmark.

Blue Ridge National Heritage Area: The Blue Ridge National Heritage Area is a federally designated National Heritage Area encompassing the twenty-five westernmost counties of North Carolina, which are associated with the Blue Ridge Mountains.  The designation provides a framework for the promotion and interpretation of the area's cultural and historic character, and the preservation of the natural and built environment.  The National Heritage Area includes the North Carolina portions of Great Smoky Mountains National Park and the Blue Ridge Parkway.  Other attractions include Mount Mitchell in Pisgah National Forest, Nantahala National Forest and the North Carolina portion of the Appalachian Trail.  The Qualla Boundary of the Eastern Band of Cherokee Indians is also within the National Heritage Area.  The area's musical heritage and folk craftsmanship are also recognized by the National Heritage Area.

North Georgia mountains: The Georgia Mountains Region or North Georgia mountains or Northeast Georgia is an area that starts in the northeast corner of Georgia, United States, and spreads in a westerly direction.  The mountains in this region are in the Blue Ridge mountain chain that ends in Georgia.  At over 1 billion years of age, the Blue Ridge mountains are among the oldest mountains in the United States and sometimes mistaken to be the oldest mountains in the world (they are only about one third of the age of South Africa's 3.6 billion year old Barberton greenstone belt.) .  The mountains in this region are also a part of the vast system of North American mountains known as the Appalachian Mountains that spans most of the United States longitudally along the eastern areas of the nation and terminates in Alabama.

Supporting paragraphs: Blue Ridge Mountains Great Appalachian Valley
Answer: Great Appalachian Valley