How did “Pomp and Circumstance” become the processional march at graduations?

"Pomp and Circumstance” was composed by Sir Edward Elgar in 1901, and was originally written for the coronation of King Edward VII, and was not intended to be used at graduations. The music became associated with graduations in 1905, when Elgar received an honorary doctorate from Yale University. At the ceremony, the recessional music was “Pomp and Circumstance.” The music made such an impression that other universities such as Princeton, Colombia, and Rutgers used it in their graduation ceremonies the following year. By the mid 1920s, most colleges and high schools incorporated the music into their ceremonies. Today, “Pomp and Circumstance” is known in the United States as the “graduation song.”

Source: http://www.npr.org/templates/story/story.php?storyId=1273081