Nov. 20, 2006  -- In several of the largest school systems across the country -- from Baltimore to Cleveland to Atlanta and Oakland, Calif. -- half of the students are dropping out.

And the problem is not only in the big cities.

A recent study by the Department of Education found that 31 percent of American students were dropping out or failing to graduate in the nation's largest 100 public school districts.

The implications from dropping out of high school are enormous, including a higher risk of poverty and even an abbreviated life span.

So why do they drop out? Eli Thomasson, 16, of Georgia, explains why he wanted to drop out of school earlier this year.

"I was just tired of school, you know. I didn't like it. I had made my mind up that I wasn't going to school anymore," Thomasson said.

His mother, Donna Thomasson, was frantic.

"Terrified," she said. "I thought his life was over. I didn't really see how I could force him to go because you can't force them to learn if they don't want to."

And Eli Thomasson wasn't the only student at his high school to consider walking away without a diploma.

Berrien High in southern Georgia is part of a national epidemic. More than 40 percent of students there do not graduate.

Sheila Hendley, Berrien High's graduation coach, has the daunting job of trying to stop this epidemic.

"I have sat with students and literally begged, 'Please don't do this,'" Hendley said. "I don't want you to have to suffer like I know you will if you don't finish school."

And in the case of Eli Thomasson, it worked. She stayed on his case and persuaded him to stay in school.

"He said, 'You know, mom. She probably just saved my life,'" Donna Thomasson said.

It is estimated that about 2,500 students drop out of U.S. high schools every day.

"It's like seeing a child in the middle of the lake that can't swim, and you see them bobbing up and down. It's like watching them drown," Hendley said.

At Berrien High, the faculty is fighting to save students who are at risk of becoming a part of that troubling statistic. "It's a real fight. Every day you talk to someone who needs to be motivated," said Berrien High School Principal Mike Parker.

And why is a high school diploma so important?

Consider this: High school dropouts have a life span that is nine years shorter than people who graduate.

Dropouts are more likely to face poverty, according to the U.S. Census Bureau.

Typically high school dropouts earn $19,000 a year. High school graduates earn $28,000 a year on average.

If you drop out of high school, your chances of running afoul of the law increase.

Nationally, 68 percent of state prison inmates are dropouts.

Sheriff Jerry Brogdon of Berrien County, Ga., sees those consequences every day at the Berrien County Jailhouse.

He said that "81.2 percent of the inmates we have in here today is high school dropouts."

Anthony White is a 17-year-old Berrien County Jail inmate.

He quit high school just two weeks before he spoke to ABC News from the jailhouse. He was arrested for allegedly firing a gun in the air just three days after he quit school.

"I felt like I was grown," White said. "Nobody could tell me not to make my own decision. That's how I felt at the time."

But White said, "Now I wish I would've listened."

James Keefe, 19, is another inmate. He dropped out of high school, too.

He has been arrested on burglary charges twice.

"When I was in school, I didn't get in no trouble," Keefe said.

On Tuesday, Pierre Thomas looks at some programs that school boards are implementing to reverse this drop-out trend. Watch "World News" for the full report.