Area coe 313 is the telephone area code serving the city of Detroit, Michigan, and some of the city's innermost suburbs, including Dearborn and Grosse Pointe. Until December 1, 1993 it served the entire Metro Detroit region plus nearby Flint and the southern part of Michigan's "Thumb", but explosive demand for new phone numbers (caused principally by the spread of fax machines and cellular phones) caused northern suburbs, Flint and the southern Thumb to adopt the new area code 810. Later, that area would be subdivided further, into 248, largely serving Oakland County, and 586, covering Macomb County. Meanwhile on December 13, 1997, the 313 area also required an additional breakup, creating the new 734 area out of Washtenaw, Monroe, and western Wayne counties.