The Palo Alto Weekly in Silicon Valley asked more than 250 residents of that city "How do you define your social class?" From the survey results (PDF):
Seventy-five identified themselves as "upper middle class." Their self-reported incomes ranged from $50,000 to $400,000 or more (with one retiree reporting $35,000-$49,999)… Eighty-one people considered themselves "middle class." Their self-reported incomes ranged from $10,000 to $399,999….Seventeen considered themselves "lower middle class" or "working class." Their self-reported income ranged from $35,000 to $349,999. Four reported being in the "upper class," three of whom reported earning $400,000 a year or more (the fourth is retired).
Eighty-nine people declined to answer the question or wrote their own answers, including that they were "disenfranchised," "former middle class" and "survivors in an unjust capitalist society."
"The meaning of 'middle class'" (Palo Alto Weekly)