Lyric discussion by epsilon343 

Cover art for Vaccination Scar lyrics by Tragically Hip, The

I had heard a while back that the song is referring to a scar that would sometimes appear after a vaccination that would usually result in the child losing their arm because of it but I can't really confirm that.

The part about the Tacoma Narrows Bridge is referring to "Galloping Gerdy" which collapsed during a windstorm as the vibrations got worse and worse. (I grew up near Seattle so it's common knowledge of the bridge around there.)

@epsilon343 All of us over a certain age carry the "Vaccination Scar" on the upper arm. It is a bit bigger than a quarter. It was done in school when we were wee lads and lasses.