What baseball traditions did William Howard Taft start?

On April 14, 1910, President William Howard Taft began the tradition of the President throwing the first pitch at the Baseball season opener. Legend has it that President Taft was also responsible for baseball's seventh inning stretch. While attending a baseball game, President Taft rose to stretch between halves of the seventh inning. The crowd (ever polite, as baseball fans are) rose in unison out of respect for the President. The tradition continues to this day.