Query: What is Detroit's area code?
Context: It is an important source of popular music legacies celebrated by the city's two familiar nicknames, the Motor City and Motown. Other nicknames arose in the 20th century, including City of Champions, beginning in the 1930s for its successes in individual and team sport; The D; Hockeytown (a trademark owned by the city's NHL club, the Red Wings); Rock City (after the Kiss song "Detroit Rock City"); and The 313 (its telephone area code).