(ABC 6 News) – The Mayo Clinic Blood Donor Center is issuing a plea, urging donors to schedule an appointment.

This comes after a drop in donations since Memorial Day, and now the clinic says they are short on O-negative blood.

According to the American Red Cross, in the United States, at some point in their lives, about a quarter of the population will need a blood transfusion.

Roughly 50% of the U.S. population is eligible to give blood, but the National Institute of Health says that only about 5% actually do.

Mayo Clinic typically has enough blood donors in the area to not have to worry about shortages.

“Mayo’s been pretty lucky; we’ve never had to cancel elective surgeries because of the committment of the blood donors and the community,” says Jeffrey Winters, a doctor at Mayo Clinic’s Division of Transfusion Medicine.

For more information on donating blood, or to schedule an appointment with the Mayo Clinic Blood Donor Center, click here.