The Rex Blood Services blood mobile was humming at the curb when I arrived, and a steady stream of students were making their way over there. More than 90 had registered to give blood.

Many local high school students donate blood. Their contributions make up nearly 50 percent of the bank’s total blood supply, said Gena Lentz of Rex Blood Services.

Rex Blood Services is owned by Rex Hospital, but it supplies blood all over the region, to Rex, UNC Hospitals, Duke and WakeMed, among others.

Lentz hopes to increase the number of high school blood drives in 2013.

“Most of our traditional drives recruit about 30 to 40 people, and with the high school drives we usually get a guarantee of 90 to 100,” she said.

That’s due in large part to student organizations like Health Occupation Students of America, which sign up students and staff members for blood drives.

“We basically make sure that kids who volunteer to donate get to their assigned time, and we make sure they get back to school, too,” said Cary High School sophomore and HOSA member Karah Wilson.

George Mullowney, a senior HOSA member, planned to donate blood for the first time.

“I just feel like people need it, and if I can give it, why not?” Mullowney said.

For Emmalei Trevathan, the blood drive hit close to home. The sophomore couldn’t donate that day because she’s not yet 17, but she has donated in the past to her critically ill mother.

“It’s definitely important because people need blood transfusions,” Trevathan said. “I definitely know about that.”

Some students said they wanted to donate blood to gain the experience.

That’s important, Lentz said.

“Usually, if they give in high school, they’ll give throughout their life,” she explained. “If we come to them and they have that experience, they can see what they’ve done. One person can save up to three lives.”

High school and college students do so much giving that when school’s out – typically summers and holidays – blood banks often run short. Basically, there’s always a need for blood. It has a shelf-life of just 42 days. Donated blood goes to patients enduring cancer and surgery as well as victims of accidents and emergencies.

High school students, it turns out, are very generous. Rex Blood Services brings its blood mobile to more than 10 Triangle high schools each year, often twice a year.

Holly Springs High School is especially a big deal. With a strong HOSA program and a large senior class, Lentz said, each blood drive at the school brings in about 300 donors.

The day I visited Cary High School, seniors had first dibs to donate blood because they could participate in the Rex Red Cord program. They get a red cord to wear at graduation to show they donated.

Lentz said Rex Blood Services will likely host another drive in January to accommodate juniors who want to donate.

Wilson is looking forward to when she can give blood. “In the future it could be you, so it’s important to provide for other people too,” she said.