The historic symbolism was also evident when Obama accepted the Democratic nomination on Aug. 28, the 45th anniversary of the late civil rights icon Martin Luther King's "I Have a Dream" speech outlining the Nobel Peace Prize winner's aspirations for black people.

In comparison, even a half-century ago, most Southern blacks weren't registered to vote because of barriers erected by white racists.

However, although the political rise of Palin and Obama did show the improvement of gender and racial equality in the United States, the "American Dream" is still elusive for many Americans, analysts said.

Although different people will have a different answer for what constitutes the "American Dream," the basic meaning is that America is a land of "opportunities," where anyone can eventually rise to the top by working hard, no matter his background, sex, or skin color.

Both major U.S. political parties may have a lot of examples of that.

For Democrats, the story of Obama is a vivid reminder of how much a black person can achieve.

Former U.S. president Bill Clinton also rose from a humble beginning.

On the Republican side, they may tell the stories of Colin Powell and Condoleezza Rice.

Now Palin, a daughter of school teachers and a common "hockey mom," also made it to the top.

However, these examples of successful "American dreams" seem to be no commonality.

The Pew Charitable Trust's Economic Mobility Project concluded in a recent report that only 6 percent of children born into the bottom socioeconomic quintile in the United States move to the very top quintile.

The conclusion was made by comparing the income of parents in the late 1960s with the income of their offspring in the late 1990s and early 2000s.