What is the economic definition of “Middle Class"?

People that get caught and squeezed in the middle. The definition is vague and politicians use their own definitions

The term middle class is political not economic, and more or less it refers to almost all voters that are not on welfare or filthy rich. Here is graph of how incomes are distributed in the US.

http://www.visualizingeconomics.com/2006/11/05/200...

As you can see it is hard to define the limits of the middle but it usually excludes only the top 1 or 2%. And here is how the federal tax burden is distributed over income groups

http://www.visualizingeconomics.com/2008/03/23/fed...

http://www.census.gov/

Lots of information. The BOC will tell you they do not define middle class with an economic range. Hence, our own Federal Government does not define a "class". They do define trends of data though. Government programs have limits imposed for determining need...that is different.