A new analysis of US government data identifies 13 states where African-American students are suspended or expelled from schools at disproportionately higher rates than white students.

While black students represented about 25 percent of public school students in these 13 southern states, they made up almost half of all suspensions and expulsions, according to an analysis by the Graduate School of Education at the University of Pennsylvania.

In some school districts, the suspension rate of black children was even more disturbing, said the study, which used data from the US Department of Education’s Office for Civil Rights.

In 132 school districts in the southern states, for example, African-American students were suspended at rates five times or more than their representation in the student population.

“I am actually shocked that there is not more outrage,” said Shaun R. Harper, associate professor of education at the University of Pennsylvania and the executive director of the Center for the Study of Race and Equity in Education who was a co-author of the analysis.

“This is at least partly attributed to people having these racist assumptions about black kids,” Harper said. “We argue that too little happens in schools of education to raise consciousness about that.”

Among the other findings in the analysis were that in 181 school districts, all of the students expelled during 2011-12 school year were black.

Within the 13 states, Mississippi and Louisiana expelled the highest proportion of African-American students.

The 13 states analyzed in the study were: Arkansas, Alabama, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Texas, Tennessee, Virginia, and West Virginia.

The striking report comes as the Obama administration and civil rights groups have focused on reducing the number of suspensions, expulsions and arrests of black students in public schools.