CHICAGO – At Sullivan High School on the city’s North Side, 479 students – the majority of them minority and low-income – enrolled in the class of 2006. By senior year, just 82 of them remained in school.

At East St. Louis Senior High School, a robust class of 777 students enrolled in the class of ’06. Fewer than half, 378, remained four years later.

A study prepared for The Associated Press by researchers at Johns Hopkins University found 1,676 high schools nationwide that held on to 60 percent or less of their students from freshman to senior year over three years – a rate that puts them in a category one researcher calls “dropout factories.”

Overall, the schools on the list are in large cities or high-poverty rural areas, and they often have high minority populations.

Illinois had 55 high schools on the Hopkins list, 9.5 percent of the 582 high schools in the state. Of those 55 schools, 35 were in Chicago Public Schools, the nation’s third-largest district.

A separate report released in July by the Consortium on Chicago School Research found that almost half of CPS students don’t graduate from high school, and at some CPS schools more students drop out than get a diploma.

Carmita Vaughan, director of the CPS Department of Dropout Prevention and Recovery, said low student retention isn’t just a CPS problem, it’s a national one.

“I really see this as a national crisis,” she said. “What have we as a country done to fail these kids?”

CPS established the dropout prevention office in 2004 after “there was recognition that we clearly had a problem and that there needed to be a district-wide approach to how we addressed the issue,” Vaughan said.

She blamed the nation’s high dropout rate – nearly a third of all students – on a one-size-fits-all approach to education.

CPS is trying to tailor its methods, and programs aimed at decreasing dropout rates include a Back to School campaign targeting students who have already dropped out and a three-year High School Transformation program that provides teacher training, stronger curricula and more outreach to students who are struggling.

Intervening as soon as students start having problems is key to keeping them in school, said Elaine Allensworth, co-director for statistical analysis at the school research consortium.

Experts said students don’t make the decision to drop out overnight but go through a process of feeling less connected and engaged at school, missing classes, failing subjects and eventually giving up.

“There may be a million reasons that students start missing class, but once they start … it’s a slippery slope,” Allensworth said. “Poor performance is the direct cause of students dropping out of school.”

In Rockford, School District 205 is trying to improve its 70 percent graduation rate with a wide-ranging program focused on retaining freshmen students, offering everything from smaller class sizes, to tutoring to innovative extra curricular activities like ballroom dancing and martial arts.