Woodrow Wilson Library Of Congress / Getty Images In 1918, Woodrow Wilson became the first sitting president to visit Buckingham Palace. From left: Edith Bolling Wilson, Queen Mary, Woodrow Wilson, King George V, and Princess Mary. Topical Press Agency / Getty Images Wilson is cheered on by crowds of Londoners during a parade in Central London. Harry Truman Carl Mydans / Getty Images, Hank Walker / Getty Images President Harry Truman being congratulated at Oxford University after receiving an honorary degree. Dwight Eisenhower Fox Photos / Getty Images President Eisenhower (centre) with the royal family in 1959. From left: Prince Philip, Princess Anne, Dwight Eisenhower, Queen Elizabeth, Prince Charles, and Captain John Eisenhower, at Balmoral Castle, Scotland, September 1959. Keystone / Getty Images Eisenhower delivers a speech to a large crowd from the balcony of Mansion House, London, on 12 June 1945. Keystone / Getty Images Eisenhower joins other politicians at a dinner party at Winfield House in London on 1 Sept 1959. Back row, from left: Field Marshal Montgomery, John Hay Whitney, Viscount Portal, Lord Tedder, Sir Brian Horrocks, and Lord Ismay. Front row, from left: Viscount Alanbrooke, Sir Winston Churchill, General Eisenhower, Lord Alexander, and Harold Macmillan. John F. Kennedy Express Newspapers / Getty Images President John F. Kennedy and his wife Jacqueline Kennedy leave Admiralty House in London after meeting with prime minister Harold Macmillan on June 6 1961. Bettmann / Bettmann Archive Prince Philip, Jacqueline Kennedy, Queen Elizabeth, and president John F. Kennedy have a chat after dinner at Buckingham Palace. Richard Nixon Pa Images / Getty Images From left: prime minister Edward Heath, the Queen, president Nixon, and first lady Pat Nixon during a visit at Chequers, 1970. Pa Images / Getty Images Queen Elizabeth II and Nixon walk through the corridors of Buckingham Palace, accompanied by the Duke of Edinburgh and Prince of Wales. Jimmy Carter Pa Images / Getty Images The Queen and president Jimmy Carter at a state dinner at Buckingham Palace on 7 May 1977 following the third-ever G7 summit. Ronald Reagan Hulton Archive / Getty Images Margaret Thatcher and Ronald Reagan outside Number 10 during a state visit to London. The "special relationship" between the two countries was founded on the rapport between the two leaders. George H.W. Bush Pa / PA Archive/PA Images Margaret Thatcher and George H.W. Bush Bill Clinton Paul Faith / PA Archive/PA Images US president Bill Clinton's cavalcade is welcomed to Carson's statue at Stormont, Belfast, during his two-day visit in November 1995. Chris Bacon / PA Archive/PA Images Bill Clinton (second from left) and prime minister Tony Blair (right) with Northern Ireland's first minister David Trimble (left) and deputy first minister Seamus Mallon (third from left) on the steps of the Parliament Buildings, Stormont, Belfast. Michael Stephens / PA Archive/PA Images John and Norma Major lead president Bill Clinton and Hillary Clinton up the stairs of Number 10, past the pictures of previous occupants of the historic home of British prime ministers, on their way to an official dinner. Anwar Hussein/ EMPICS Entertainment The Queen meets (from left centre) Hillary, Bill, and Chelsea Clinton at Buckingham Palace. George W. Bush Kirsty Wigglesworth / PA Archive/PA Images US president George Bush and the Duke of Edinburgh during an inspection of the guard of honour at Buckingham Palace. A traditional 41-gun salute marked the start of the historic state visit. Chris Ison / PA Archive/PA Images Queen Elizabeth II and the Duke of Edinburgh stand alongside Bush and his wife Laura on the forecourt of Buckingham Palace in London at the start of the president's state visit to Britain. Barack Obama Fiona Hanson / PA Archive/PA Images US president Barack Obama and Michelle Obama outside Downing Street in London where they were greeted by prime minister Gordon Brown and his wife Sara ahead of the G20 Summit in April 2009. John Stillwell / PA Archive/PA Images The Obamas talk with Queen Elizabeth II and the Duke of Edinburgh at Buckingham Palace. Gareth Fuller / PA Archive/PA Images Barack and Michelle Obama are greeted by David and Samantha Cameron outside Downing Street as the US president embarks on a three-day state visit to the UK in May 2011. Anthony Devlin / PA Archive/PA Images Barack and Michelle Obama during the ceremonial welcome by Queen Elizabeth II and the Duke of Edinburgh in the garden of Buckingham Palace as part of their state visit to the UK and Ireland. Paul Hackett / PA Archive/PA Images Obama and Cameron play table tennis at Globe Academy in South London. Chris Jackson / PA Archive/PA Images Queen Elizabeth II and the Duke of Edinburgh pose with Barack and Michelle Obama in the Music Room of Buckingham Palace ahead of a state banquet. Donald Trump Tolga Akmen / AFP / Getty Images Donald Trump and first lady Melania Trump disembark Air Force One at London Stansted Airport on July 12, 2018, as he begins his first visit to the UK as president.