It is one of our emblems because it represents how much of the rest of the world sees us. It represents the "good life" or the "easy life" and that's what we Americans have. It represents the idea that we are materialistic and like to have things easily available to us (right there in the can or bottle).
I think it is challenging to identify a single reason as to why the Coca- Cola brand is a part of American identity. Part of this might have to do with the brand's incessant footprint on American advertising. Since its inception in the the late 19th Century with Hilda Clark as a sponsor, it is difficult to see a time where Coca- Cola was not a significant presence in American culture. The Red and White colors of the logo became linked to Santa Claus, a cultural icon of America. In the 1940s, the jingle of "Coke means Coca- Cola" flooded the airwaves. Celebrity sponsorship and an appeal to the youth helped to advance the brand in the 1950s and 1960s, with the infectious, "I'd Like to Teach the World to Sing," song of the 1970s. With Cola Wars in the 1980s and Coke being victorious, the brand had become an established presence in American culture. The product's designers had intended that was to ensure that everyone on Earth drank Coca-Cola as their preferred beverage. This is especially true in southern areas of the United States such as Atlanta, where the product was born. With such aims, the brand has become a part of American identity and has been seen as one of its exports to the world in both good and bad elements.