On March 15th, 1937—86 years ago this week— a new kind of bank opened in the US. That bank wouldn’t deal out money— it would deal out blood. Blood banks would help to revolutionize medicine, save countless lives, and make complex new surgeries possible. But who could put blood in those banks? Who couldn’t? And why? That has its own complicated history. One that we’ll look at through an event that happened not too long ago.