Imagine you are very sick and need blood right away. Before 1937, a doctor would have to find a healthy person willing to give blood at that exact moment. If no one was available, there was nothing else to do. A doctor named Bernard Fantus wanted to fix this problem. He figured out how to collect blood, test it, and keep it cold so it stayed fresh. On March 15, 1937, he opened the world's first blood bank at Cook County Hospital in Chicago. He even invented the name "blood bank." People came in and donated their blood. Nurses labeled each bag with the blood type. When a patient needed a transfusion, the matching blood was already waiting. Before Fantus, getting blood to a patient was a race against time. After him, hospitals could plan ahead. His idea spread fast. Within a few years, blood banks opened across the country. During World War II, blood banks saved thousands of wounded soldiers. Today, the Red Cross collects about 6.8 million units of blood every year in the United States alone. One person's donation can save up to three lives.