An Economic Definition of the Middle Class

The concept of a middle class is prevalent in both common parlance and the social sciences; concern is frequently expressed that the middle class is shrinking, and politicians often position themselves as champions of the middle class. Yet the phrase “middle class” is extremely ambiguous; no consensus exists on either the upper bound or the lower bound separating the middle class from other classes. The present paper employs the government’s official poverty line as the demarcation between the poor and the middle class, and develops an equivalent distinction to separate the middle class from the wealthy. Based on the new definition, the paper provides some rough empirical estimates of the size of the American middle class over the 1989--2004 period.