PITTSBURGH — The tradition for a fall Monday here is to engage in the true national — or at least regional — pastime: celebrating a Steelers’ win on Sunday or complaining about what in the world has gotten into the offense.

But this Sunday, like a breaking newscast in the middle of a tight game, in came politics: on the sideline and in the locker room and pretty much everywhere else.

If the ground under the N.F.L. shook from the national debate over race, patriotism, protest and the president, Pittsburgh might have in some ways felt like the epicenter. With teams across the country finding ways to respond to President Trump’s disparaging comments about the league and some players, the beloved Steelers took a drastic approach. As the national anthem played before their game in Chicago, the entire team, except for one player, stood inside the tunnel instead of standing on the sideline.

The town’s professional hockey team, the Penguins, meanwhile, confirmed that it would, in fact, accept an invitation to visit the White House as winners of last season’s Stanley Cup.