Poolesville High School in Montgomery County and Thomas Jefferson High School in Fairfax County tied for the best four-year graduation rates in the Washington area, according to data the U.S. Department of Education released Tuesday.

At both schools, 99 percent of the class of 2011 graduated in four years, the data shows. The lowest rates at traditional high schools in those counties were at Wheaton High School in Montgomery County, which graduated 74 percent of the class of 2011, and at J.E.B.