Income inequality in the United States is among the most extreme in the world.
It is often repeated that the wealthiest 10% of American households control nearly 75% of household net worth. This is income inequality. In the U.S. stagnating wages over the last few decades have shrunk the middle class. According to a recent Pew Research Center study: "Among the top 5% of households – those with incomes of at least $248,729 in 2018 – their share of all U.S. income rose from 16% in 1968 to 23% in 2018."
According to the report, "The share of American adults who live in middle-income households has decreased from 61% in 1971 to 51% in 2019. During this time, the share of adults in the upper-income tier increased from 14% to 20%, and the share in the lower-income tier increased from 25% to 29%."
Corporate CEO's earn 320 times more than the average worker, according to the Economic Policy Institute. That's up from 61 times more than the average worker in 1989.
There is additional inequality between the incomes of Black and White families, with median black household income only 61% of median white household income in 2018, again according to the Pew report.
In 2017 data from the Organization for Economic Cooperation and Development (OECD), only four other nations -- Bulgaria, Mexico, Chile and Costa Rica -- have greater income inequality.
The U.S. is ranked 9th worst of 15 countries in a 2019 report in USA Today, "Countries With the Widest Gaps Between Rich and Poor," that considered 15 both relatively wealthy OECD member states and non-OECD member states. In this survey the U.S. is more equal (very relatively speaking) than Turkey, Chile, Mexico, Brazil, Costa Rica, India, China and South Africa.
The report notes that, unlike those of other countries, U.S. tax and social safety net programs do little to close the income gap: "With a GDP per capita of $53,632 and an unemployment rate of 4.4%, the U.S. economy appears healthy. But the benefits of a strong economy are not evenly enjoyed by all Americans. Of the 325.1 million Americans, an estimated 17.8% live below the poverty line. U.S. taxes and transfers do a relatively poor job of leveling out the economic playing field. While most nations' Gini coefficients decline by more than 30% after taxes and transfers, the U.S. Gini coefficient declines by only about 23%." (The Gini coefficient ranks nations' income equality on a scale of 0 to 1.)