The American President traditionally takes to the mound on the opening day of the season
The Major League Baseball season begins on Sunday afternoon.
On Opening Day, the Washington Nationals play the Florida Marlins in Nationals Park. Each year, the United States President is invited to throw the ceremonial first pitch in the Nationals' first home game of the season.
The 2017 season will be the first since Donald Trump became President in January. As is tradition, the President was invited to throw the first pitch, but he has turned it down due to a "scheduling conflict".
Nats say the White House has declined invitation for President Trump to throw out ceremonial first pitch Opening Day.— Barry Svrluga (@barrysvrluga) March 28, 2017
While the tradition does not take place annually, William Taft was the first President to take to the mound in 1910. 12 further Presidents have followed in Taft's footsteps.
Barack Obama was the last President to throw the pitch. He did so in 2010, to mark the 100th anniversary of Taft's first pitch.
While Trump will not take part in the tradition this year, he is a noted baseball fan. in 2006, he threw the first pitch in a match between the Boston Red Sox and New York Yankees at Fenway Park.
The President also sang 'Take Me Out To The Ball Game' at Wrigley Field during a Chicago Cubs game in 2000.
While Trump has turned down the chance to throw the first pitch this year, he still has at least another three opportunities to do so during his Presidential reign.