About western Usa cowboy?

Why, having in the American continent and also in the United States more people working with cattle on a horse besides the cowboy from the western US, is the former the most famous and only this has been put on films, even creating a dedicated cinematographic genre (the Western)? For instance, the cracker from Florida. Nobody knows it outside the US and hasn't been put on films. Look the western cowboy; everybody knows him. Why such differences?