[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2010/images/04/05/art.obama.pitch.gi.jpg caption ="President Obama threw out the first pitch Monday at the Washington Nationals' home opener."]Washington (CNN) - President Barack Obama continued a century-old baseball tradition among the nation's chief executives Monday, throwing the ceremonial first pitch at the Washington Nationals' home opener against the Philadelphia Phillies.
The southpaw president took the mound at a packed ballpark shortly after 1 p.m., tossing a pitch that flew high and outside.
Obama wore a Nationals jacket, but also donned a cap from his favorite hometown team, the Chicago White Sox.
Presidential William Howard Taft started the tradition on Opening Day of the 1910 season. The Washington Nationals defeated the Philadelphia Athletics that day, 3-0. Eventual Hall of Fame pitcher Walter Johnson threw a one-hitter.
"Washington has been the historic place for presidential first pitches," said John Odell, curator of history and research at the Baseball Hall of Fame in Cooperstown, New York.
When there was no baseball team in Washington, presidents sometimes went to other places such as Baltimore, Maryland, or Cincinnati, Ohio, long host to the first baseball game each season.
"President Nixon went to his home state of California," Odell noted.
Presidential pitching styles can vary, with some better than others.
"President Dwight Eisenhower may have been the best," Odell said. "It was rumored he played for a semi-pro team while at West Point."
When members of the White House press corps asked questions, Odell said, "they were told not to look into it any further."
Presidents Harry Truman and Gerald Ford threw out first pitches both right- and left-handed. Odell said President George W. Bush "had particularly good form."
Presidents have not always thrown the first pitch from the mound. In fact, that tradition didn't start until recently. It used to be that a first toss was thrown from the box seats, as Taft did in 1910.
Although this tradition goes back a century, sometimes a president can't make Opening Day because he's just too busy. In 1912, Taft couldn't throw out the first pitch because the Titanic had just sunk.
"President Franklin D. Roosevelt made it a regular habit during his early years in office," Odell said, "but during the war years, he didn't."
Many times, when the president is otherwise engaged, he sends the vice president or a member of his Cabinet. President Jimmy Carter never threw out an Opening Day pitch while he was in office, Odell said. "Carter once told a friend the demands of the White House and the presidency were too busy, by coincidence, during those times."
Carter later threw the first pitch for a World Series game after he was out of office.
"A first pitch says a lot about how a president ought to behave," Odell said. "We want him to take the job seriously but not so seriously that he can't take a few hours to come out and be a regular guy like the rest of us and enjoy our national pastime."
As for Obama, he has a history of throwing out first pitches. He did it at a Chicago White Sox game in 2005, while he was a U.S. senator, and again at last year's All-Star game in St. Louis, Missouri.
–CNN's Bill Caiaccio contributed to this report