North Carolina currently utilizes 9 area codes. When first established by AT&T and the Bell System in 1947, 704 covered the entire state of North Carolina. The most recently added was 743 in 2016 as an overlay to 336. Today, 704 is the most populated with an estimated 2.1 million of the state's 9.5 million residents.
Sources: North American Numbering Plan Administration (NANPA), telecom providers, and the U.S. Census Bureau.