The achievement gap - the gap between test scores of low income students and wealthier students - widened in North Carolina more than in any other state between 2011 and 2014, according to the Education Equality Index.
The Education Equality Index is a national measure of the achievement gap that includes city and state information.
The index measured achievement gaps at schools in six North Carolina cities, Raleigh, Durham, Winston-Salem, Greensboro, Fayetteville, and Charlotte in 2014. Five of the six were determined to have "massive" achievement gaps, while Charlotte had a "large" achievement gap.
A massive gap is defined as students from low income families reaching proficiency at a lower rate than students from other low income families, on average. A large achievement gap is defined as low income students reaching proficiency at a higher rate than other low income students, but at a lower rate than all students, on average.
Most of the 100 cities in the index have massive achievement gaps, said Christine Schneider, Education Equality Index spokeswoman. "North Carolina cites are not alone," she said.
Raleigh and Durham have larger achievement gaps than 90 percent of major American cities.
The index is funded by the Michael & Susan Dell Foundation and was developed in partnership with Education Cities and GreatSchools.
The index highlights the challenges faced by schools with high percentages of high-poverty students, said Brenda Berg, president and CEO of BEST NC, a business coalition focused on improving education in the state.
"With poverty levels at record highs in America, the need for schools that can provide a great education for children from poor communities is growing," Berg said in a statement. "This tool from the Education Equality Index (EEI) shows that the hard work educators are putting in to level the playing field for our low-income students is critical and must be expanded."