A few months before her father King George VI died in February 1952, Princess Elizabeth and her husband Prince Philip, Duke of Edinburgh, were hosted in Washington by President Harry Truman and his family. On that trip, her first to the United States, she also visited the Library of Congress. Queen Elizabeth II would return to the U.S. for state visits several times over the years, and she revisited the Library in 1991. An item of particular interest to her on that second visit, reportedly, was a condolence letter from her great-great-grandmother, Queen Victoria, to Mary Todd Lincoln following the assassination of President Lincoln. Years later, in 2015, Queen Elizabeth II would surpass Queen Victoria as the the longest-reigning British Monarch in history. As such, she will be remembered as an enduring and stalwart figurehead during times of great change in her own nation and across the world. Image: From the Harry S. Truman Library. October 31, 1951. From left to right, Margaret Truman, Mrs. Bess Wallace Truman, President Harry S. Truman, Princess Elizabeth of England, and her husband the Duke of Edinburgh, Prince Philip. The groups greet each other as the Princess and Prince step off their airplane.