Nelson played his last concert before dying in a plane crash on New Year's Eve 1986 (December 31, 1985). Huntsville, Alabama, nicknamed "the Rocket City", has risen to be the center of north Alabama economic activity since the dawn of the space age in the 1950s. It is now the largest city in Alabama. Its aerospace and military technology centers of Redstone Arsenal, Cummings Research Park, and NASA's Marshall Space Flight Center define the high-tech landscape for Alabama. Knoxville, Tennessee, the most populous metropolitan area in the valley, is where the Tennessee River begins at the confluence of the Holston and the French Broad Rivers. Knoxville along with nearby Oak Ridge and Maryville-Alcoa, form a major research and manufacturing corridor anchored by the University of Tennessee, the Oak Ridge National Laboratory, and the Tennessee Valley Authority headquarters (since 1980). Muscle Shoals, Alabama, considered part of the Shoals along with Florence, Sheffield, and Tuscumbia, is a major city of northwest Alabama, along U.S. Route 72 and Alabama 157. The city is located immediately across the Tennessee River from Florence. (The river divides Colbert County from Lauderdale County.) Muscle Shoals is famous for its 1960s Muscle Shoals Sound, produced at such studios as FAME Studios and Muscle Shoals Sound Studio, where many famous musicians and bands, such as Aretha Franklin, Bob Dylan, and The Rolling Stones, also have recorded and produced numerous songs. Tuscumbia is the birthplace of Helen Keller. The original Congressional Act creating the government owned Tennessee Valley Authority, May, 1933, designated the government reservation at Wilson Dam as the location for the headquarters of the TVA. In 1980, a court order reassigned the headquarters to Knoxville. Scottsboro, Alabama, about from Chattanooga and nicknamed "the Friendly City", is located on Highway 72, east of Huntsville. It was founded in the mid-1850s and is most famous for the Scottsboro Boys and the Unclaimed Baggage Center, as well as "First Monday," an open-air marketplace held in and around downtown on Mondays following the first weekend of the month. Transportation Interstates connects Paducah, Kentucky, at the mouth of the Tennessee River, with Chattanooga via Clarksville and Nashville. Much of this road's route in Kentucky and Tennessee actually lies outside the Tennessee Valley. is an east-west main route of the Interstate Highway System in the Northeast Tennessee. It runs from the junction of U.S. Route 11W and U.S. Route 23 in Kingsport, Tennessee, generally