* "Sweeping" as a metaphor for popularity: "Sweeping" implies a wide-reaching effect, like a broom cleaning a floor. It's been used figuratively for a long time to describe things that are widespread and popular. For example, you might say a "sweeping change" or a "sweeping victory."
* "Nation" as a symbol of widespread appeal: "Nation" denotes a large, unified group, making it a natural fit for expressing something that has become widely popular across a country.
* American cultural context: The phrase likely gained popularity in the US, where the concept of "sweeping the nation" aligns with the country's large size and emphasis on popular culture.
Therefore, "sweeps the nation" is likely a natural evolution of language, combining common metaphors and cultural concepts to express a trend that is widely popular and influential. There's no single origin point, but rather a gradual emergence of the phrase over time.