<P> Economist Branko Milanovic argued that globalization and the related competition with cheaper labor from Asia and immigrants have caused U.S. middle - class wages to stagnate, fueling the rise of populist political candidates such as Donald Trump . </P> <P> The relatively high rates of health problems and social problems, (obesity, mental illness, homicides, teenage births, incarceration, child conflict, drug use) and lower rates of social goods (life expectancy, educational performance, trust among strangers, women's status, social mobility, even numbers of patents issued per capita), in the US compared to other developed countries may be related to its high income inequality . Using statistics from 23 developed countries and the 50 states of the US, British researchers Richard G. Wilkinson and Kate Pickett have found such a correlation which remains after accounting for ethnicity, national culture, and occupational classes or education levels . Their findings, based on UN Human Development Reports and other sources, locate the United States at the top of the list in regards to inequality and various social and health problems among developed countries . The authors argue inequality creates psychosocial stress and status anxiety that lead to social ills . A 2009 study conducted by researchers at Harvard University and published in the British Medical Journal attribute one in three deaths in the United States to high levels of inequality . According to The Earth Institute, life satisfaction in the US has been declining over the last several decades, which has been attributed to soaring inequality, lack of social trust and loss of faith in government . </P> <P> It is claimed in a 2015 study by Princeton University researchers Angus Deaton and Anne Case that income inequality could be a driving factor in a marked increase in deaths among white males between the ages of 45 to 54 in the period 1999 to 2013 . </P> <P> Paul Krugman argues that the much lamented long - term funding problems of Social Security and Medicare can be blamed in part on the growth in inequality as well as the usual culprits like longer life expectancies . The traditional source of funding for these social welfare programs--payroll taxes--is inadequate because it does not capture income from capital, and income above the payroll tax cap, which make up a larger and larger share of national income as inequality increases . </P>

What is the level of income inequality in the us