The Charlotte-Mecklenburg School District earned the 2011 Broad Prize for Urban Education, showing the greatest student achievement gains in the nation, the Eli and Edythe Broad Foundation announced on Tuesday.

The Broad Foundation recognizes school districts that show improvement in bridging achievement gaps between ethnic and income groups, the foundation said in a press release. A panel of 21 judges, including three former U.S. Secretaries of Education, made the selection. The school district will receive $550,000 in college scholarships for its graduating high school seniors.

More than half of Charlotte-Mecklenburg's 136,000 students are African-American or Hispanic, and more than half qualify for reduced-lunch programs.

The school district narrowed the achievement gap between minority students and white students in reading and math at all school levels. The number of low-income students who performed at North Carolina's highest achievement level in middle school and high school math and reading also increased faster than any other district in the state.

"Charlotte-Mecklenburg is a model for innovation in urban education," U.S. Secretary of Education Arne Duncan, who attended the awards ceremony, said in the release. "It has taken on the tough work of turning around low-performing schools, created a culture of using data to improve classroom instruction, and put a laser-like focus preparing students for college and careers."

The three other finalists for the Broad Prize -- Broward County Public Schools and Miami-Dade County Public Schools, both in Florida, and the Ysleta Independent School District in El Paso, Texas -- will each receive $150,000 in college scholarships for graduating seniors.