President Donald Trump's visit to the Queen during his trip to the UK marks the latest in a long history of meetings between the British monarch and US heads of state.
In her 66-year reign, Queen Elizabeth II has met nearly all of the 12 presidents in office during that time, with the exception of Lyndon B Johnson and Mr Trump.
Here is a selection of photographs from the monarch's meetings with past presidents.
The Queen with President Dwight D Eisenhower at a White House state banquet, in 1957. Eisenhower is wearing the British Order of Merit awarded him by King George VI after World War Two.
At Buckingham Palace during a banquet held in his honour, President John F Kennedy (right) and his wife, First Lady Jacqueline Kennedy (second left), pose with the Queen and Prince Philip in 1961.
The Queen and Prime Minister Edward Heath meet President Richard Nixon (second from right) and his wife Pat (right) at Chequers, Heath's official country residence, in 1970.
President Gerald Ford dances with the Queen during the 1976 Bicentennial celebrations of the Declaration of Independence at the White House.
The Queen with President Jimmy Carter at a state dinner at Buckingham Palace in 1977.
The Queen rides in the grounds of Windsor Castle with President Ronald Reagan during his state visit to the UK in 1982. The horses were gifts to the Queen from the Royal Canadian Mounted Police.
The Queen with President George H W Bush in Washington DC, USA, in 1991.
President Bill Clinton and his wife Hillary meet the Queen at Buckingham Palace in London in 2000.
President George W Bush welcomes the Queen at the White House during her six-day trip to the US in 2007.
The Queen and Prince Philip pose with President Barack Obama and his wife, Michelle, ahead of a state banquet at Buckingham Palace in 2011. The 44th President of the United States was in the UK for a two-day state visit.
Photographs subject to copyright.