The middle class is a somewhat arbitrarily defined class of people who are neither very rich nor very poor. The middle class definitely includes the middle fifth household income quintile and usually is regarded as including at least part of the second and fourth quintiles as well, with the second being considered "lower middle class" and the fourth being considered "upper middle class." From 2008 to 2012, the percentage of Americans considering themselves part of the middle class fell from 53 percent to 49 percent, while the percentage considering themselves part of the lower class rose from 25 percent to 32 percent and the percentage considering themselves part of the upper class fell from 21 percent to 17 percent.
There is some debate as to whether the middle class is shrinking. According to Richard Burkhauser, between 1979 and 2007, in U.S. dollars adjusted for inflation, "the income of households between the 60th and 80th percentiles grew by 40 percent, and those in the 40th to 60th percentile grew by nearly 40 percent."
- Shenker-Osorio, Anat (1 August 2013). "Why Americans All Believe They Are 'Middle Class'". The Atlantic.
- Haskins, Ron (29 March 2012). "The myth of the disappearing middle class". Washington Post. http://articles.washingtonpost.com/2012-03-29/opinions/35450048_1_income-distribution-income-inequality-income-growth.