Only 4 percent of schools have closed the economic achievement gap, according to the Education Equality Index. Brownsville, Texas, a border town with high poverty rates and many Spanish-speaking families, does the best at educating low-income students, according to the index, a project of GreatSchools and Education Cities. Eight of the top 10 cities are in Texas, including El Paso and McAllen, notes Lauren Camera in U.S. News. In Brownsville, 95 percent of students are poor,