One of the most fascinating things about the United States is our musicality. Our pop music is full of complex rhythms, and we clap on 2 and 4 – which practically no one else in the world does (I am leaving out our influence on neighboring cultures like Canada and the UK).
Germans clap on 1, 2, 3, and 4, and the unbearable season of Carnival is about to begin filling up evening TV with such clapping. To get an idea of how terrible German clapping is, take a look at this video clip I've put together of two TV shows. The first is an afternoon cooking show, and it begins every day with a demonstration of Germans' incapacity to clap. It then segs into a nightly TV show on which a young (and quite rhythmically adapt) German guitarist plays an easy-to-follow rock song, but the audience nonetheless cannot clap to its rhythm.
Now, you might argue that the audience may not have been able to properly hear the music in the studio, though that seems doubtful in the second case, where the boy is standing in front of a stack. But no matter, it is hard to imagine any composer counting in Beethoven's Fifth with "a one, a two, a one two, three four"; classical music is nearly bereft of rhythm as we understand it in pop music, and German pop also remains quite straightforward rhythmically.
Indeed, the same could be said for large parts of Europe. As one American funk musician once said of Abba, they never were quite as big in the US as they were in Europe because they are "100 percent funk-free."
Obviously, at some point Americans also clapped on 1, 2, 3, 4 (or one & three, depending on how you count), so when did we switch over? Fascinatingly, I have found a video on YouTube of chubby Checker singing "The Twist," and if you listen to the first minute, you will hear the audience clapping on 1 & 3 – the way, Germans do even today to pop, swing, funk, etc. But just after the first minute, the crowd seems to lose its bearing, and by 1:20 the audience has switched over to clapping on 2 & 4 the way, Americans would automatically do today – though they can't keep it up.
Unfortunately, the video does not indicate when it was recorded, but "The Twist" was first recorded in 1959 and became a hit for chubby checker in 1960. I imagine the US did not switch to clapping on 2 & 4 all at once. Rather, the people listening to "race records" (as R&B was originally referred to) probably started it off, and in that chubby Checker video we are witnessing the last vestiges of white-bread America around 1960 not yet clapping as we Americans all do today.