Twenty One Pilots is not known for subtlety, so the signals to the crowd Wednesday night at Madison Square Garden, where the duo played the first of two sold-out shows to close the United States leg of its Emotional Roadshow tour, were bold.

They were there when the singer and pianist Tyler Joseph announced that performing at the arena was a dream realized, adding, “We did it,” and then took more than a minute to define “We.” (In amateur video of the speech posted to YouTube, a fan’s gentle sobs are audible as he speaks.) And when the drummer Josh Dun played a small kit on a platform held aloft by the fans crammed into the pit. And when Mr. Joseph ended the show, as he usually does, telling the crowd, “We are Twenty One Pilots … and so are you.”

Dedicated young fans have quietly made Twenty One Pilots the biggest band of 2016. And Twenty One Pilots have quietly become a gifted arena act.