Blood donations have fallen to a four-year summer low, according to the American Red Cross. (Michael Cavazos/Longview News-Journal File Photo)The American Red Cross is calling on Americans to donate blood amid a life-threatening shortage. The leading blood drive organization has declared the second national blood crisis in its history, and medical patients who need blood “may already be feeling the impact,” the organization’s leaders said in a statement. People who cannot attend one of the above blood drives can book appointments at other blood drives by using the Red Cross Blood Donor App, visiting RedCrossBlood.org or calling 1-800-733-2767. People can also donate blood to Carter BloodCare, another blood drive organization serving the region.