President William Howard Taft started the American tradition of Presidential first pitches in 1910 at Griffith Stadium, Washington, D.C., on the Washington Senators' Opening Day. Every President from Taft to Obama has thrown out at least one ceremonial first ball or pitch, either for Opening Day, the All-Star Game, or the World Series, usually with much fanfare.[5] The current President, Donald Trump, has yet to throw a ceremonial first pitch, though has done so for Minor League games prior to taking office
https://en.wikipedia.org/wiki/Ceremonial_first_pitch