The American Red Cross encourages eligible donors to give blood this summer, helping to ensure a sufficient supply for patients in need.Blood donations tend to decline during the summer, when many regular donors are on vacation and schools are out of session. However, the need for blood is constant. All blood types are currently needed, especially O negative, which is the universal blood type and can potentially be transfused to any patient.Upcoming blood donation opportunities:Ellinwood — 2-7 p.m. Friday, June 21, at Ellinwood High School, 210 E. Second.Larned — noon to 6 p.m. Friday, June 28, at the Larned Community Center, 1500 Toles.To donate blood, call 1-800-RED CROSS (1-800-733-2767) or visit redcrossblood.org to make an appointment or for more information.