What is the total wealth of the United States? The hardest part about this is figuring out the value of labor, which is by far the greatest part of wealth, and is also much less concentrated than capital. Poterba's article (see below) at least mentions this; Wolff's does not.

U.S. GDP in 2004 is about 10 trillion dollars. Suppose we assume that this will grow at 2% per year (per capita GDP growth has averaged 2.1% over the past 10 years), and suppose we discount it at 5% (a reasonable figure for a risky asset). That gives us a net discount rate of 3%, so the present value is 10/.03 = 333 trillion dollars.

The BEA says non-labor wealth equals 39 trillion. Add 5 trillion for government wealth. Then multiply by 4, because labor's share of GNP is about 75% (see Krueger article). This yields 44*4 = $176 trillion.

Dividing these figures by 300 million yields an average value for a life of .586 to 1.11 million dollars.

Perhaps, though, we should be using median wealth rather than mean wealth. Mean income is 57 thousand dollars per household and the median is 41 thousand, so median wealth-- if proportional to income-- is 41/57=.71 times as high as mean wealth. This would give us a value for a life of $416,000 to $788,000.

We might or might not want to subtract out the portion of wealth owned by the government--18.9%, if proportional to income.

How about looking at it from the point of view of an individual? 40 years of undiscounted earnings of $30,000/year equals 1.2 million dollars. So that puts us in the correct range also. (Suppose someone starts at $30,000 per year and then their salary increases at a rate of 5% per year, In 40 years their salary would be abour $210,000. So this is an overestimate.)

Sources:
Statistical Abstract, 2003. Table 680. Money income of households: median was 41,000. Mean is 5978,107/(104539) = 57,000 in 2000.
Table 709: 2001 median family net worth was 86K, mean was 395K.
Table 710. Household and nonprofit net worth in 2002 was 39 trillion.
Table 659. GDP in 2002 was 10.4 trillion dollars. 18.9% of that is government.
Table 666. Per capita GDP rose 2.1% annually over the past 10 years.

Measuring Labor's Share, Alan B. Krueger, The American Economic Review, Vol. 89, No. 2, Papers and Proceedings of the One Hundred Eleventh Annual Meeting of the American Economic Association. (May, 1999), pp. 45-51.
Stock Market Wealth and Consumption, James M. Poterba, The Journal of Economic Perspectives, Vol. 14, No. 2. (Spring, 2000), pp. 99-118.
Recent Trends in the Size Distribution of Household Wealth, Edward N. Wolff, The Journal of Economic Perspectives, Vol. 12, No. 3. (Summer, 1998), pp. 131-150.