Yellowstone: Elk traffic jam

It's a constant joke that you see inscribed on mugs and t-shirts in all Yellowstone souvenir shops: if you are late to meeting someone, just claim that you got stuck in a buffalo traffic jam. Not only they stop the traffic when they cross the road, but they do it even if they are just standing nearby - since everyone wants to take a peek. So that's how you know if there is something interesting ahead - don't look for the wildlife but look for people looking for wildlife. We got stuck in a traffic jam like that, only this one was caused by elk: