Queen Elizabeth II, currently the world's longest-reigning monarch, turns 94 years old on April 21, 2020.

Since 1951, the year before she ascended to the throne, the Queen has met with 12 US presidents and helped facilitate the US and UK's diplomatic relations.

Here's what the queen's relationships and meetings with US presidents have been like from Harry Truman to Donald Trump.

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Queen Elizabeth II turns 94 years old, today, April 21.

The queen, who ascended to the throne in 1952 and is currently the world's longest-reigning monarch, has played a major role in facilitating the US and UK's "special" diplomatic relationship and has met with 12 American presidents at places including Buckingham Palace, the White House, and even a Baltimore Orioles game.

President Donald Trump and First Lady Melania Trump last visited with the royals from June 3-5, 2019 on a special state visit to commemorate the 75th anniversary of D-Day.

They attended several distinctly British meet-and-greet opportunities, including tea with heir Prince Charles, a banquet at Buckingham Palace, a tour of Westminster Abbey, and a D-Day anniversary ceremony, most of which was alongside royalty.

The queen traveled to Washington, DC for the first time to meet President Harry Truman in 1951 when she was still a princess, and has also hosted Trump at Windsor Castle when he visited England in 2018.

Here's what the queen's relationships and meetings with US presidents have been like, from Harry Truman to Donald Trump.