the united states , like other countries has its rich and poor people , its rich and poor neighborhoods.
americans love --- and many are themselves living examples of ---the "self -made man. " you will hear this expression often. but for every person who is successful. they are usually better educated tan their parents and therefore more likely to have good , well paying jobs.
in addition to the fact that the united states includes people whose families came from many other parts of the world , americans move across the nation in great numbers. one study reported that one of every five families in the united states moves every three years . this continuous mixing of people into new communities is an important observation to consider when to understand the meaning of class in america. we have already discussed the questioning , "do-it -yourself" american personality that is another important consideration.
in many countries, a man's social class is determined at birth . that is , his social class or position is shared with his family , his wider group of relatives . in the united states , position in society is , to a large degree, personal rather than to family or group.
before world war two, family ties were more important america than they are now . uncles, aunts grandparents , and children vacationed together, spent holidays together, and saw much of each other. but as the american economy developed more rapidly after the war, social customs began to change. with the rapidly growing economy , there were new employment opportunities, many of them in scientific fields. these opportunities were often located in other parts of the country . the younger members of many families who were will educated began to move away from the towns where their families lived to tale these new jobs. as these young people became successful, they often moved into a new social , consisting of others who, like themselves ,moved away from home to follow job opportunities.
these same changes are already in most new countries around the world . today , a man who can read or fix a machine may become the new leader of his in place of an older person. often young people can better understand the new sciences and modern skills ; as these young people learn and advance , their wages rise and they become successful.
frequently ., it is just one member of a family that becomes very successful. other members continue working at their average jobs and salaries , without much chance of becoming as successful as the son or daughter. when this happens , people sometimes become separated from their family. many return to visit, but others move away never to return to their relatives and old friends.
to many people , success means having more power than one possessed before . it can be won through skill, knowledge , , or sometimes just by hard work . in america, "success" has bee accompanied by an increase in wealth. as a result , an individual 's social position is determined bot by a person's job and by the kinds of possessions he owns .
as we said , however, young people are in the process of developing different values and different ways to measure success.
 n. [地] 地层, [生](组织的)层, 社会阶层
excerpted from " a guide to u.s.a. ", edited by li yang, li yi, published by foreign language teaching and research press.