Played loud on a good sound system (5.1), the last 15 seconds of that song are awesome, especially the last note sung.
When everyone all cease singing together, that theater reverberates for almost 2 seconds before the audience claps.
Perhaps the sound engineers of that film utilized the convolution reverb, the “acoustic fingerprint” of that theater to produce this breathtaking sound.
The performance of the song rings in our souls, because we feel our country is being destroyed. Even before the events of modern times, we have that feeling in our gut. When spontaneous singing, praying, or an event that evokes emotion, it simply triggers emotional crying.
I remember my folks crying when Kate Smith sang God Bless America. It reminded them of the time when people were united, and needed to be.
If they only knew how much of the events of the early 20th Century were scripted and manipulated to destroy the economy. Get us into Wars for Empire, and destroy the money supply. They likely do, and weep from the grave.