A common refrain used in American political rhetoric today is that 'the middle class is disappearing in the US and that the rich are taking a larger share of the economic pie at the expense of the lower and middle classes.'

This line of argument has been repeated so often, it now part of the Conventional Wisdom, and therefore, say those repeating it, a problem the government needs to address.

However, these accepted facts seems to be contradicted by national exit-polling data collected in the election cycles from 2000-2010 (there was no exit-poll data for 2002; also, the data does not total to 100% in every year due to rounding):

Percentage of Vote by Income (Less than $50k)

2000 47%
2002 ND
2004 45%
2006 40%
2008 37%
2010 36%

Percentage of Vote by Income ($50-100k)

2000 38%
2002 ND
2004 37%
2006 38%
2008 36%
2010 36%

Percentage of Vote by Income (More than $100k)

2000 15%
2002 ND
2004 18%
2006 23%
2008 26%
2010 27%

While the exit-poll data on household income has not been adjusted for inflation for the period from 2000-2010, note that it shows the percentage of voters coming from households making less than $50k per year has decreased by more than 20% over that time span, that the group making between $50k-$100k has shrunk by about 5%, and that the group making more than $100k has grown by 80% from 2000-2010.

So on a percentage-point basis, almost all of the shrinkage in the 'less-than $50k' income group of voters during the past decade has been mirrored by the growth in the 'over $100k' income group, with the $50k-$100k income group of voters remaining roughly stable to slightly smaller.

That certainly doesn't appear to fit the narrative very neatly, at least when using the voting public as the sample group.