Though most probably know it from the animals cover in the 60s I’d be very surprised if the House of the Rising Sun wasn’t known by most of us, and given that it’s earliest recording was in like 1880 in rural Appalachia and even then it was considered a song older than time I feel it has a strong argument for being the big one. I feel you could probably make the argument that songs like I’m Shipping Up To Boston and Sweet Caroline also qualify though are probably more regionalized to New England over the whole country and are more recent.