Income Mobility & Inequality

Gini index measures the extent to which the distribution of income or consumption expenditure among individuals or households within an economy deviates from a perfectly equal distribution. A Lorenz curve plots the cumulative percentages of total income received against the cumulative number of recipients, starting with the poorest individual or household. The Gini index measures the area between the Lorenz curve and a hypothetical line of absolute equality, expressed as a percentage of the maximum area under the line. Thus a Gini index of 0 represents perfect equality, while an index of 100 implies perfect inequality. [source]

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Income inequality can be measured and compared using something called the Gini coefficient, a century-old formula that measures national economies on a scale from 0.00 to 0.50, with 0.50 being the most unequal. The Gini coefficient is reliable enough that the CIA world factbook uses it. Here's a map of their data, with the most unequal countries in red and the most equal in green...The U.S., in purple with a Gini coefficient of 0.450, ranks near the extreme end of the inequality scale. Looking for the other countries marked in purple gives you a quick sense of countries with comparable income inequality, and it's an unflattering list: Cameroon, Madagascar, Rwanda, Uganda, Ecuador. A number are currently embroiled in or just emerging from deeply destabilizing conflicts, some of them linked to income inequality: Mexico, Côte d'Ivoire, Sri Lanka, Nepal, Serbia. Perhaps most damning is China, significantly more equal than the U.S. with a Gini coefficient of 0.415. [source]

 The U.S Income Distribution & Income Mobility

Ultra Rich Pulling Away From Everyone Else

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In 2011, 4.48 percent of all income in the United States was captured by the top 0.01 percent of Americans — a group of less than 16,000 households (or “tax units” in IRS parlance). That’s actually down from a peak of 6.04 percent in 2007. Of the top 10 years for the top 0.01 percent, eight have come since 2000; the other two were 1928 and 1929, right before the Great Depression.

The average member of the top 0.01 percent made $23,679,531 in 2011; the cutoff for membership in the group was $7,969,900. That’s a good deal less than 2007, when the average member of the group made $38,016,760. For comparison, the average member of the bottom 90 percent made $30,437 in 2011 and $35,173 in 2007.

Until the 1970s, the bottom 90 percent had actually seen its income grow more than any other income group. The income gap was shrinking. But the ultra-rich quickly reversed that trend. In 2007, the top 0.01 percent had an average income almost seven times that of 1917; the average income of the bottom 90 percent had barely tripled. The country has grown more unequal, not less, since then.