From an article in the Charlotte Observer:
The Hickory and Newton-Conover districts will join 20 states and the District of Columbia that have increased the dropout age to 18 or have voted to do so in coming years. Backers of the legislation, including June Atkinson, state superintendent of public schools, say they hope the Catawba County effort will eventually spread statewide.
The article also noted that empirical evidence (PDF) does not support the belief that raising the compulsory attendance age will reduce dropouts.
A 2012 study concluded that raising the dropout age “and thinking that the problem has been addressed may not quite be shuffling the deck chairs on the Titanic, but it comes close.” The study found little evidence to support a connection between high school graduation rates and the compulsory school attendance age. “If some students receive some benefit as a result of raising the compulsory school attendance age, it is rational for a state to set (the) age at 18,” said the report by the Brown Center on Education Policy at the Brookings Institution in Washington, D.C.