There is some income mobility in the United States, but it is not as high as in some other developed countries. Studies have shown that children from low-income families are less likely to move up the income ladder than children from high-income families. However, there is still significant movement up and down the income ladder over time. While some of the rich remain rich, others move down the income ladder, and some of the poor move up. The degree of income mobility varies by region, race, and other factors, but overall, there is some movement up and down the income ladder in the United States.