According to Simmel (1904-1971), people form higher levels of the stratification system constantly try to distinguish their consumption habits from that of people from lower levels.
For example, when it comes to fashion, people from the elite tend to show their capacity to afford the latest trends. But people from lower levels of the stratification system usually copy those trends in cheaper versions, forcing the elites to continuously update their wardrobe to the latest trends. The same applies to other forms of consumption, such as cars, activities and even ideas.
The primary geographical feature that served as a boundary to westward settlement in 1760 was the Appalachian Mountains, since these were very high and treacherous and gave people very little incentive to cross.
