What was Myrtle's "tragic achievement" in The Great Gatsby?

In Chapter VIII, Nick sees Gatsby alive for the last time, but he has to go to the city and leave Gatsby on his own.  He describes taking the train and crossing to the other side of the car when the train goes through the valley of ashes and passes the spot where Myrtle had been killed by Gatsby's car.  He describes the way he imagines young children still "[search] for dark spots in the dust, and some garrulous man [tells] over and over what had happened [...]."  For now, everyone is still terribly and morbidly interested in Myrtle's death, but, eventually, the children will stop looking for blood in the dirt and the man will tell the story of her death so many times that he will grow tired of the telling, and it will stop seeming like a real event.  Thus, when Nick says that Myrtle's "tragic achievement" will be forgotten, he is referring to her death.  It is the major event of her life -- the violence and drama of her death -- and it is really the only story about her that will be told again and again because she accomplished nothing else of general interest.