those songs you just can't get out of your head an it's suddenly being downloaded all over again. You might have seen neil diamond's visit to boston. But no one, not even neil diamond, saw what was... See More
those songs you just can't get out of your head an it's suddenly being downloaded all over again. You might have seen neil diamond's visit to boston. But no one, not even neil diamond, saw what was coming next. I bring love from the whole country. Reporter: We showed neil diamond's visit to boston's fenway park just days after the marathon bombings. He came to sing "sweet caroline," his song that has long been a sort of boston anthem. ♪ Reaching out touching me, touching you ♪ Reporter: And those red sox fans were ready. ♪ Sweet caroline ♪ Reporter: But what neil diamond did not know was that song would become a hit all over again. So many people downloading it in just one week after the bombings, sales up 600%. And he was asked about the sudden surge -- I think there's a little bit of god in that song. I always have felt that. There's no accounting for what can happen to a song, but this one had something special to it. Reporter: The song is more than 40 years old. He once said, he wrote about a young caroline kennedy. He's even joked, he couldn't get the song out of his own head. Nor can people all over america. ♪ Touching handing ♪ ♪ reaching out ♪ ♪ touching me ♪ ♪ touching you ♪ ♪ sweet caroline ♪ ♪ ba ba ba ♪ here is neil diamond. Reporter: He had no idea this song would still be playing long after that performance on ed sullivan in 1969. ♪ Sweet caroline ♪ Reporter: More than 125 million albums sold. And tonight, the song selling again. Are you ready? ♪ Sweet caroline ♪ ♪ ba ba ba ♪ Reporter: All these years later, neil diamond saying he'll donate all the proceeds of that song to the great town of boston. And so we choose neil diamond and his fans across the country for downloading that song again all to support boston.
This transcript has been automatically generated and may not be 100% accurate.