First, and probably the main thing, on the list should be dry comfortable, clothing to put on after the race so you can change out of your wet race gear. Pack warm, loose-fitting clothing that’s easy to pull on like sweatpants, sweatshirts, a jacket, socks, and comfy sandals or shoes.
It’s common to get chilled after the race because of fatigue or dehydration, so layers are helpful. Depending on your race, you may have a long walk back to your hotel or car, or you may need to use public transportation. Consider how long you will be out in the elements and how far you may need to walk afterward when it comes to how much fresh clothing you need to pack.
It’s also nice to pack a small towel or some wet wipes for cleaning up quickly after that hard race. Another consideration for you to pack would be compression socks; they are helpful because they aid venous return in your legs, which is important for recovery.
Comfortable shoes are also a must-have. It’s great to get out of your running shoes after a long race, but be certain to pack shoes or sandals you can walk in comfortably. A final thing to add to your bag might be a specific food or drink you want (or need!) that is not available at the race. One runner I know always packs a diet soft drink and a bag of pretzels in her bag.
Another important note: It’s best to keep valuables with you rather than to check them in this bag. Things like keys, money, ID, phone, or medications may fall out of the bag, so it’s better to keep those things on you or in a safe location.