What is considered upper middle class in the US?

Answer:

Well, there is a lot of ambiguity about what is and what is not considered middle and upper middle class.
According to sociologists such as Dennis Gilbert of Hamilton College the upper middle class constitutes about 15% of households. Its members are very highly educated professionals with great autonomy in the work place. Graduate degrees are very common and educational attainment serves as the main distinguishing feature of this class. (Gilbert, 2002; Ehrenreich, 1989) Household incomes vary depending on how many income earners there are within a household. One-earner upper middle class households may have incomes in the high 5-figure range while married couple household commonly have incomes in excees of $100,000. (Gilbert, 2002; Thompson & Hickey, 2005) In 2005, the top 15% of personal income for individual earners were those making $62,500 or more. (US Census Bureau, 2006)
References:

1. Gilbert, D. (2002). The American Class Structure: In An Age Of Growing Inequality. Belmont, CA: Wadsworth.
2. Ehrenreich, B. (1989). Fear of Falling: The Inner Life of The Middle Class. New York, NY: Harper-Collins.
3. Thompson, W. & Hickey, J. (2005). Society in Focus. Boston, MA: Pearson, Allyn & Bacon.
4. US Census Bureau. (2006). Personal Income Statistics for 2005. 14 June, 2007 taken from http://pubdb3.census.gov/macro/032006/perinc/toc.htm