The survey shows nearly eight out of 10 Americans believe it is still possible to get ahead in the current economy.

And 72 percent believe their economic circumstances will be better in the next 10 years.

John Morton

But some economists say there's little reason for optimism. "The median income for men in their 30s has fallen by about 12 percent over the last generation. Forty-two percent of children born to parents at the bottom of the income distribution remain in that same bottom quintile a generation later," said John Morton, head of the Pew Economic Mobility Project.

For much of U.S. history, Americans experienced income growth and upward mobility.

But since 1973, according to the project, growth in family income has slowed and income inequality has increased.

The outlook for African Americans is especially bleak. The research shows that almost half of black children, whose parents were middle-income, end up falling to the bottom of the income ladder.

The United States stands out as having less economic mobility than many other industrialized countries including Canada, Denmark and France.

Ray Boshara of the New America Foundation says many low-income people in the United States believe strongly in their ability to move up. But net worth is critical. "Families that have stocks, families that have homes, savings, what can they do with that? They have a cushion to fall back against, they have resources with which to make investments, they have assets, they have things they can pass onto the next generation," he said.

Researchers with the project are presenting their findings to policymakers in a bid to improve economic opportunity in the United States.