The U.S. Department of Education today released four-year high school graduation rates for the 2010-11 school year that, for the first time, reflect a common method of calculation for all states.

The state-by-state data show graduation rates that range from 59 percent in the District of Columbia to 88 percent in Iowa. The new method requires states to track individual students and report how many first-time 9th graders graduate with a standard diploma within four years.

UPDATE [11/28, 2:36 p.m.]: Even though the Education Department billed this release as the first time the common rate has been used by all states, it’s important to point out—as a loyal reader in Kentucky did for me—that three states still aren’t using the new method. Kentucky, Idaho, and Oklahoma have requested, or been approved for, timeline extensions that will give them more time to report their rates.

According to the department, the new, common metric “can be used by states, districts and schools to promote greater accountability and to develop strategies that will reduce dropout rates and increase graduation rates in schools nationwide.”

Today’s data show glaring achievement gaps. In Minnesota, for instance, the graduation rate for black students was 49 percent; for white students, it was 84 percent. In Ohio, the graduation rate for economically disadvantaged students was 65 percent; for all students it was 80 percent.

The release of this data comes as advocacy groups are calling on the department to strengthen graduation rate accountability in the waivers being issued under the No Child Left Behind Act. These groups are criticizing U.S. Secretary of Education Arne Duncan for allowing states to violate the spirit—if not the letter—of the 2008 regulations that mandated a common graduation rate.