WASHINGTON (AP) — The Education Department says high school graduation rates for most states continue to improve. Many states also are showing gains for black and Hispanic students.

The department says preliminary data show graduation rates up in 36 states for the 2013-2014 school year. The biggest gains were in Delaware, Alabama, Oregon, West Virginia and Illinois. Five states had declines, including Alaska, Hawaii, Nevada, Oklahoma and New Mexico. The District of Columbia also slipped.

Eight states were flat; Idaho did not have complete numbers to report. Education Secretary Arne Duncan says the nation appears to be on track to take another step toward higher graduation rates. The nation's overall graduation rate is 81 percent, an all-time high. Final data is due next spring.