LOS ANGELES

Amid the verdant lawn and leafy trees of the tidy Jefferson Senior High School campus, you'll see something troubling: a police officer patrols the grounds and a sign warns that guns are illegal.

The biggest problem here, however, is what you don't see -- all the dropouts.

With a 58 percent dropout rate, Jefferson has the worst record in the Los Angeles Unified School District. The district average is 33.6 percent, compared with a statewide average of 24.2 percent, according to recent state figures.

"It's horrendous," said Debra Duardo, director of the dropout prevention and recovery program at LAUSD, the nation's second-largest district.

While half the students typically quit urban schools nationwide, Jefferson is at the lower end of the spectrum of so-called "dropout factories" because of a concentration of factors that are rarely all present at schools in other cities.

Located in South Los Angeles, where new immigrants mostly from Mexico and Central America settle, the area has a large minority population and high poverty.

Of its 1,977 students last school year, 45 percent qualified as English learners. More than 90 percent qualified for free or reduced-price lunches.

The newcomer population means families shift quickly, following jobs or fleeing immigration raids. The school has a 57 percent transience rate, compared to a 38 percent average across district high schools.

"There's a lack of well-paying jobs in the area," said social studies teacher Nicolle Sefferman. "When folks have a chance to move on, they move on."

A vast number of students are raised by single parents who struggle to support their families, financially and emotionally, and Principal Juan Flecha noted that many students do not live with their parents, who work in other cities or even in other countries.

A shift in demographics has spurred racial divisions that peaked three years ago when African Americans and Latinos clashed in several bloody melees.