President Obama threw the opening pitch at the 2005 Chicago White Sox-Anaheim Angels game.

Keating Holland
Director, CNN Political Unit

When Barack Obama steps on the mound at tonight's All-Star game in St. Louis to throw out the ceremonial first pitch, it will be only the fifth time in the 76-year history of the All-Star game that a president has done so, and the first time in more than 30 years.

Presidents routinely perform this task at Opening Day festivities and less frequently at World Series games, but a presidential appearance at the Midsummer Classic is rare. Here is a list of presidential first pitches at All-Star games:

July 7, 1937 F. Roosevelt – Threw out first pitch
July 10, 1962 Kennedy – Threw out first pitch
July 14, 1970 Nixon – Threw out first pitch
July 13, 1976 Ford – Threw out first pitch
July 14, 2009 Obama – Scheduled to throw out first pitch

George H. W. Bush attended the 1991 and 1992 all-star games but did not throw out the first pitch on either occasion. In 1991, the game was held in Toronto, and Bush probably deferred to his host, Canadian Prime Minister Brian Mulroney. (News reports indicate that Mulroney decided not to throw out the first pitch because he risked getting booed. Canadian-born Hall of Famer Ferguson Jenkins did the honors.) It's less clear why Bush didn't throw out the first pitch in 1992, when he had Mexican President Carlos Salinas de Gortari as his guest. Bush, as Vice President, threw out the first pitch at the 1988 All-Star game in Cincinnati as a presidential candidate.

In 1978, Gerald Ford threw out the first pitch, but he was an ex-president at that time.

In 1989, Ronald Reagan was in the broadcast booth and did an inning of color commentary (1st inning) but did not throw out the first pitch and was not president at that time.

This is not the first time Obama has thrown out the first pitch at a baseball game (he did the honors at a 2005 Chicago White Sox playoff game while still a U.S. Senator), but it is the first time he will do so as president.