A Hymn Singing Tradition

There are very few places where people get together and sing anymore. Church is perhaps the only place left in America where this still happens consistently.
When I first came to the States, I was struck by the silence at sporting events. In the UK, crowds sing and chant together--often unrepeatable versions of popular songs--but over here, there are cheerleaders who do most of the cheering on behalf of the crowd. Even during the national anthem most folk stand silently clutching their ball caps.  When did Americans stop singing their own national anthem at public events? Is it a misplaced mark of respect? Is it because it has become a performance by the diva on the field rather than a community coming together in song?
All I know is it wouldn't happen in Wales!
In Wales they sing their national anthem. Here is a fine example of congregational singing outside of a church context:

A Welsh Apostolic Pentecostal Missionary once complained to me that if you get a welshman drunk, he starts singing hymns but you'll never get him to go to chapel. They will sing hymns when led by Tom Jones:

They will also break into CWM RHONDDA spontaneously when they get excited: