A state-by-state examination of trends in income inequality over the past two business cycles finds that inequality has grown in most parts of the country since the late 1980s. The incomes of the country's highest-income families have climbed substantially, while middle- and lower-income families have seen only modest increases.

In fact, the long-standing trend of growing income inequality accelerated between the late 1990s and the mid-2000s (the latest period for which state data are available).

On average, incomes have declined by 2.5 percent among the bottom fifth of families since the late 1990s, while increasing by 9.1 percent among the top fifth.

In 19 states, average incomes have grown more quickly among the top fifth of families than among the bottom fifth since the late 1990s. In no state has the bottom fifth grown significantly faster than the top fifth.

For very high-income families - the richest 5 percent - income growth since the late 1990s has been especially dramatic, and much faster than among the poorest fifth of families.

Similarly, families in the middle of the income distribution have fallen farther behind upper-income families in many states since the late 1990s:

On average, incomes have grown by just 1.3 percent among the middle fifth of families since the late 1990s, well below the 9.1 percent gain among the top fifth. Income disparities between the top and middle fifths have increased significantly in Alabama, California, Florida, Illinois, Mississippi, Missouri, New Mexico, and Texas. Income disparities did not decline significantly in any state.

The benefits of economic growth were broadly shared for a few years in the late 1990s - the only period in the past two decades for which this was true - but this broad-based growth ended with the 2001 downturn. Once the effects of the recession were left behind, the trend toward greater inequality quickened, as the incomes of the richest families climbed while those of low- and moderate-income families stagnated or declined.