At the close of World War I, the anthem was played, and many saw it as a symbol of unity and patriotism. Tens of thousands of people may come together under the banner of the flag by having the song played during sporting events, particularly baseball games.
It didn’t take off right away, but during WWII it gained momentum again. Before there were motion pictures and plays, it was all around us. While many teams just persevered, it was in Vietnam that it essentially became a full-fledged norm.
The national anthem is largely only played in the US before to domestic events. Some perceive it as a political game that resembles brainwashing. Some regard it as a sign of respect for the nation and flag, or patriotism.
Still others believe it to be fake patriotism and that it isn’t demonstrated by beating hearts and waving banners. Others view it as a sign of respect for the soldiers who took part in past conflicts and/or those public officials who put their lives in danger every day to keep us safe.