HILLSBOROUGH (AP) — An Orange County chapter of the NAACP is asking the school board to enact a ban on the Confederate flag.

The News & Observer of Raleigh reports Northern Orange County NAACP President Patricia Clayton sent a letter to Superintendent Todd Wirt asking for a ban on school grounds, citing other districts that prohibit it on school property, clothing and other materials. The letter didn’t identify those districts.

Clayton said that having to demonstrate that the flag disrupts the learning environment is symptomatic of racial and cultural bias in the district.

School officials couldn’t be reached for comment Tuesday.

In 2015, the Northern Orange NAACP sought a ban on the Confederate flag on student clothing after a rally in Hillsborough drew 600 people in support of the flag.