Elvis Presley receives the Salk polio vaccine in 1956. Awareness about the vaccine led to the end of polio in the U.S. Most babies today still receive the injection. Photo courtesy of March of Dimes. April 12, 1955, was…

Margaret Thatcher's death on Monday rehashed the debate about the former British prime minister's legacy. Headlines from "The Woman Who Divided a Nation" to "The Woman Who Saved Britain" piled on newsstands across London. Photo by Peter Macdiarmid/Getty Images…