I thought it was in 1973 when ABBA won the Eurovision Song Contest with "Waterloo".
Sorry to disappoint you,but the venue where the rally is being held is Named after The 5 Sullivan Brothers,judging by the photo in your post and your comment indicates you are ignorant of the notable event.
I hope it was just an oversight,maybe you have just been blinded by your blind support of someone who claims to be a conservative.
In my experience,if someone has to claim to be something,whatever it may be,usually means the evidence is not self evident and they probably are not what they claim to be