She was the only living Presidential widow from May 19, 1994 to June 5, 2004. This was the period between the death of Jacqueline Kennedy Onassis and the day when Nancy Reagan was widowed. Lady Bird Johnson died on July 11, 2007. Lady Bird Johnson was 94 years old. She was the oldest First Lady alive until her death. She had even outlived Pat Nixon, who was First Lady after Johnson. Only one First Lady had lived longer: Bess Truman. Bess Truman had lived up to 97 years of age. Lady Bird Johnson, Bess Truman, Nancy Reagan and Betty Ford are the only four First Ladies to have lived over 90 years or more. The United States Secret Service continued to protect her until she died.