The two hours after the USA vs. the World competition ends are the classic example of a dénouement.
Sure, there are plenty of races, and a lot of the fans stick around for them. They even get pretty excited for the high school boy's 4x400-meter Championship of America.
But it's pretty clear that everyone, from fans to administrators, is exhausted. So as the infield slowly clears out, the mood becomes a lot more laid-back.
A lot of people sit on the infield instead of standing, and those who move around do so a lot more slowly than they did before. It's clear that things are coming to an end,
Then, as the sun starts setting one more time, the last college 4x400 goes off in front of an almost barren infield. As the last runner crosses the line, the last few fans make their way down the steps in the seating bowl and head out into the evening.
Click on the link above for photos of some of the last few big moments at this year's Penn Relays.