The shape of the income distribution is not itself a subject of legislation, but Members of Congress appear to consider it in their decision-making process concerning a number of policy issues such as taxes, means-tested benefits, and social insurance programs. Congress also takes up legislation specifically in the name of those in the middle (however defined) of the income distribution who commonly are referred to as the middle class. Some Members have, for example, proposed bills to improve U.S. competitiveness as a means of increasing exports manufactured by workers in "good" (middle-class) jobs (such as P.L. 111-240 , the Small Business Jobs Act of 2010). Similarly, training policy generally has been crafted to provide individuals with the skills thought necessary to attain a middle-class standard of living (see, for example, P.L. 105-220 , the Authorization of the Workforce Investment Act). This report first presents a brief analysis of the distribution of income across households in 2012, the latest year for which annual data are available from the Census Bureau. It then attempts to put the term middle class into greater perspective: first, by applying results from public opinion surveys on social class to the Census Bureau's data on the income distribution in 2012 and, second, by reviewing findings from empirical studies on the contribution of relative (as opposed to absolute) income to the identity of the middle class. The Census Bureau conducts a survey from which it derives annual estimates of the distribution of income across households, families, and individuals with income. Households, which are more numerous than families, appear to be most relevant to the discussion here because household members are assumed to pool whatever income they have and share a common standard of living. The bureau's official measure of income is money income . It includes earnings, interest, dividends, pensions, child support, and government non-means-tested income (e.g., Social Security benefits, unemployment compensation, and veterans' payments). Money income is calculated on a pretax basis; that is, it excludes payments for personal income taxes, Social Security, Medicare, union dues, etc. It also excludes the value of noncash means-tested benefits (e.g., food stamps, public housing subsidies), employer-provided fringe benefits, and capital gains. Money income is the measure on which official estimates of poverty are based. Data describing the distribution of income across households can be presented in a number of ways. The top portion of Table 1 displays the number and share of households with income by income class. The income class sizes range from about $5,000 toward the lower end of the distribution to about $50,000 at the upper end of the distribution. In 2012, 2.1% of households (2.549 million out of 122.459 million) had incomes between $200,000 and $249,999, for example. Another 2.4% of households (2.911 million out of 122.459 million) had incomes of $250,000 or more. (The Census Bureau does not disaggregate income within the group of households with incomes of $250,000 or more.) At the lower end of the distribution, 3.4% of households (4.204 million out of 122.459 million) had incomes of less than $5,000. The concentration of income among the relatively few households in the upper tail of the income distribution can be seen by comparing two summary measures of the shape of the income distribution shown in the last two rows of Table 1 . One summary measure, median income, is the level below and above which one-half of all households lie. It is generally considered a better indication of the income of the "typical" household than is the mean (average), which can be pulled up by a relatively small number of high-income households in the upper end of the distribution. One-half of households had income above the median of $51,017 in 2012, whereas many fewer households (about one-third) had income above the mean of $71,274. Another often-used way to describe the distribution of income is the share of total money income going to different household groups in order of increasing income. In 2012, there were a total of 122.459 million households with income, so each quintile (fifth) in the distribution represents 24.492 million households. The Census Bureau separately calculates the total income share of the top 5% of households. As shown in Table 2 , the top 5% of households accounted for 22.3% of all income in 2012. By comparison, the lowest quintile (20%) of households had only 3.2% of aggregate income. The Congressional Budget Office (CBO) produces annual estimates of the U.S. income distribution that combine information from the Current Population Survey (CPS) with Statistics of Income (SOI) compiled by the Internal Revenue Service. This richer data set allows CBO to construct a broader definition of household income than found in the Census's money income estimates. Major sources of difference in CBO's estimate of household income are the inclusion of capital gains and the value of noncash benefits (such as food stamps, Medicare and Medicaid, and employer-paid health insurance premiums). The use of the SOI also allows CBO to compute after-tax income by subtracting estimates of federal income and corporate taxes, social insurance (payroll) taxes, and excise taxes from before-tax income. Because SOI data are not as timely as Census data and because of the computational scope of the task, the most recent CBO income distribution estimate is for 2010 (released in December 2013). As shown in Table 3 , CBO's estimate of the 2010 distribution of household income is broadly similar to the Census estimate. However, because of transfers and taxes, CBO's estimate of the income distribution is modestly more equal than the Census estimate (for 2012). CBO's broader treatment of transfers increases the share of income in the lowest quintile. In addition, CBO's consideration of the federal tax system decreases (relative to CBO's estimate of the before-tax share) the after-tax share of the highest quintile and increases the shares of the four lower quintiles. Although Congress often considers legislation specifically in the name of the middle class, there is no official government definition of the group, and it is not the aim of this report to develop one. What constitutes the middle class is subjective and comparative, meaning different things to different people. The term may refer to a group of people with a common point of view or similar incomes. Most people likely have decided views as to whether they are middle class, and those who refer to the middle class have a rough idea of whom they have in mind. How closely these definitions correspond is another matter. Any discussion of the middle class necessarily starts with those at the very middle of the income distribution. As previously discussed, median household income was $51,017 in 2012. How far the middle class stretches above and below the median is the question. A narrow view of the middle class might include only those in the middle (third) quintile, that is, those households with money income between $39,736 and $64,553 in 2012 (see Table 2 ). It seems unlikely, however, that so narrow an income range would account completely for those commonly considered to be middle class. For that reason, the three middle quintiles are often combined to broaden the definition. In 2012, according to this broader definition, the 73.476 million households with income above $20,592 and below $104,087 might have composed the middle class. These households accounted for 60% of all households in the distribution and a smaller share (45.7%) of total income in 2012. A still broader definition of middle class can be constructed by adding that part of the top quintile up to the point at which the top 5% of households begins. In 2012, then, 91.842 million households with incomes above $20,592 and below $191,150 might have composed the middle class. These households accounted for 75% of all households in the distribution and a slightly smaller share (74.4%) of total household income in that year. The results of opinion surveys offer further insight into the income bounds that may define the middle class. A few surveys asked people to indicate their social class. In a 2005 New York Times survey, for example, 35% of respondents identified themselves as working class and 7% said they were part of the lower class. Another 42% considered themselves to be middle class, and 15% said they were part of the upper middle class, whereas 1% of respondents identified themselves as members of the upper class. In contrast, the top income class ($250,000 or more) in the Census Bureau's detailed data on the household income distribution shown in Table 1 accounted for 2.3% of all households. Assuming some correspondence between the survey responses and Census income data, this discrepancy suggests that the 15% of respondents who said they were upper middle class includes some households with incomes over $250,000. Comparing just the 42% of respondents who reported being middle class with the Census data suggests the upper bound of the middle class might instead be lower at somewhat under $125,000. The lower bound of the middle class might be just over $40,000, based on a comparison of the 42% of respondents who reported they were working or lower class with the Census data. The National Opinion Research Center (NORC) at the University of Chicago began asking people in 1972 to identify their social class in the General Social Survey (GSS). The cumulative results of self-reported class divisions in the GSS can be compared with the Census income distribution as was done above with the Times survey. According to the 1972-2010 GSS data, 3.2% of the population consider themselves to be upper class. This would put the dividing line between middle and upper class at somewhat over $200,000.