Memphis is hollowing out.

That’s the conclusion of research by the Brookings Institution.

Earlier this week, we suggested that Memphis Mayor Willie W. Herenton read research about Memphis instead of relying on political insiders to convince him that their pet projects (think tax freezes) are the only things that keep our city from oblivion.

The recent report on middle-income neighborhoods would be a good place to start. While the Brookings Institution painted a trend that is hollowing out of U.S. cities, few did worse than Memphis.

It’s a conclusion that indicates more and more that our city is becoming a city of extremes – the rich stay because they can afford to live anywhere and the poor stay because they have no choice. It’s the middle income families that are voting with their feet and it’s a mandate of discontent.

The percentage of middle-income families in the largest 100 metros in the U.S. fell from 28 percent in 1970 to 21.5 percent in 2005. Meanwhile, the percentage of middle-income neighborhoods fell from 58.2 percent to 40.9 percent over the same period of time.

In Memphis in 2000, 19.9 percent of families were middle-income and 29.7 percent of neighborhoods. In fact, in the list of 100 largest metros, Memphis was 88th in the share of middle-income families and 98th in neighborhoods.

The report concludes that we are witnessing a shrinking proportion of families with middle incomes and an even faster decline in neighborhoods with middle income character. It is a polarization that could ultimately create greater political conflict and spirited competition for scarce resources.

While City Hall may be focused on preserving the largesse of the local PILOT program, a widening disenchantment with city services and a growing feeling that no one is in charge are driving more and more people to make the decision to leave Memphis.

The 2005 Memphis Poll is instructive in this regard.

Heading the list of concerns is crime protection, with 85 percent of the public saying it is government’s highest priority. Undoubtedly, that percentage could only have climbed after this week’s killing fields.

In 1996, only 18 percent of Memphians said they were concerned about gangs and crime in their neighborhoods. It had climbed to 30 percent in 2005.

Meanwhile, the falling confidence in City Hall is reflected in other indicators, such as the perception of parks. Four years ago, the perception was 86 percent positive. Today, it’s 72 percent. As for the physical condition of neighborhoods, only 10 percent were concerned in 1993, but that has climbed to 28 percent in 2005.

It seems obvious that it will take something dramatic to convince an increasingly cynical public that city government can be transformed. But it could begin by making Memphis a city of choice for the middle class.