Only 59 percent of high school students who started as freshmen in the 2006-2007 school year graduated four years later from District of Columbia schools, according to the data, which details state four-year high school graduation rates in the 2010-11 school year.
That compares with a 76 percent rate during 2009-2010.
There were 71,284 students in 191 schools in the District of Columbia, which is not a state but comprises the nation’s capital city. The district received $98.3 million dollars in federal funding during 2011.
Second from the bottom is Nevada, the home state of Senate Majority Leader Harry Reid (D-Nev.), with a 62 percent graduation rate.
At the top of the list, meanwhile, Iowa stood alone, with an 88 percent graduation rate.
Wisconsin, the home state of GOP vice presidential candidate Paul Ryan, tied for second-best with Vermont, posting a graduation rate of 87 percent.
Delaware, the home state of Vice President Joe Biden, had a 78 percent graduation rate, while California – home of House Democratic Leader Nancy Pelosi (D-Calif.) – stood at 76 percent.
Other selected state rates:
Top Tier
Iowa -- 88 percent
Vermont -- 87 percent
Wisconsin -- 87 percent
North Dakota -- 86 percent
New Hampshire -- 86 percent
Nebraska -- 86 percent
Indiana -- 86 percent
Tennessee -- 86 percent
Texas -- 86 percent
Middle Tier:
Illinois -- 84 percent
Massachusetts -- 83 percent
Virginia -- 82 percent
Ohio -- 80 percent
Arizona -- 78 percent
Washington -- 76 percent
West Virginia -- 76 percent
Mississippi -- 75 percent
Michigan -- 74 percent
Bottom Tier:
Alabama – 72 percent
Louisiana -- 71 percent
Oregon -- 68 percent
Georgia – 67 percent
New Mexico -- 63 percent
Nevada - 62 percent
DC -- 59 percent
The 2010-11 graduation rates are preliminary, state-reported data, according to the federal government and the Education Department says it will release final rates in the coming months. Education Secretary Arne Duncan said this is the first year for which all states used a common measure.