Data released by the Census Bureau this morning shows a widening gap in income distribution for many states, reflecting a decades-long trend as more wealth shifts to the most affluent Americans.

The Gini coefficient, the standard measurement of income inequality, climbed by a statistically significant margin in 20 states from 2010 to 2011, the Census Bureau reported. The index was statistically unchanged in all 30 other states and the District of Columbia, with no states recording a decrease.

This isn’t a surprise, as income inequality has continually expanded in recent years. U.S. household income inequality has increased about 18 percent since 1967, with much of the growth occurring in the 1980s, according to another Census Bureau report published earlier this year.

Data indicates the South and parts of the northeastern U.S. experience the greatest degree of income inequality. This divide is much clearer when measuring inequality for smaller geographic regions, such as counties.

The Census Bureau measures household income inequality using the Gini coefficient, which ranges from 0 to 1. High values represent a greater disparity, so a population with all equal incomes would register a coefficient of zero.

New York (0.503), Connecticut (0.486) and Louisiana (0.484) recorded the highest 2011 income inequality, while Wyoming (0.408) and Alaska (0.410) had the least disparity.

The Gini coefficient measured in the following ten states showed the largest year-over-year increase:

State 2011 Gini Estimate 2011 Margin of Error 2010 Gini Estimate 2010 - 2011 Difference
West Virginia 0.4721 0.0089 0.451 0.0211
New Mexico 0.4821 0.009 0.464 0.0181
Nebraska 0.4467 0.0094 0.432 0.0147
Maine 0.4509 0.0089 0.437 0.0139
North Dakota 0.4448 0.0101 0.433 0.0118
Arkansas 0.4684 0.0061 0.458 0.0104
Michigan 0.4612 0.0029 0.451 0.0102
California 0.4812 0.002 0.471 0.0102
New Hampshire 0.4347 0.0092 0.425 0.0097
Oregon 0.4586 0.0069 0.449 0.0096

States with higher 2011 estimated income equality are shaded dark blue in the map below.

Click a state to display its data. A greater Gini coefficient represents higher income inequality, with margins of error shown in parenthesis.

NOTE: Zoom out to view Alaska and Hawaii data.

Today's release was part of the first set of data published from the Census Bureau's 2011 American Community Survey.

Other new survey data now available includes poverty, health insurance, housing and numerous other figures. Check back in the coming weeks as we'll be posting more data from the release.