Social mobility has always been a hallmark of the United States open class system.
Mobility can either be upward or downward change.
There are several kinds of social mobility. Vertical mobility means that an individual actually moves from one social class to another. An example of this kind of mobility would be a person who moves up from the working class to the middle class. Another kind of mobility is known as horizontal mobility . In an open class system such as ours, each social class is very large.