A:Thanks for the question!
The answer isn't completely straightforward, because economists have many definitions for what makes up the money supply.
On page 3 of my article What is deflation and how can it be prevented? I look at the three main definitions economists have of the money supply. Another good place for information on the money supply is The Federal Reserve Bank of New York. The New York Fed gives the following definitions for the three money supply measures:
"The Federal Reserve publishes weekly and monthly data on three money supply measures -- M1, M2, and M3 -- as well as data on the total amount of debt of the nonfinancial sectors of the U.S. economy... The money supply measures reflect the different degrees of liquidity -- or spendability - that different types of money have. The narrowest measure, M1, is restricted to the most liquid forms of money; it consists of currency in the hands of the public; travelers checks; demand deposits, and other deposits against which checks can be written. M2 includes M1, plus savings accounts, time deposits of under $100,000, and balances in retail money market mutual funds. M3 includes M2 plus large-denomination ($100,000 or more) time deposits, balances in institutional money funds, repurchase liabilities issued by depository institutions, and Eurodollars held by U.S. residents at foreign branches of U.S. banks and at all banks in the United Kingdom and Canada."
We can figure out how much money there is in the United States per person over 21 by taking each measure of the money supply (M1, M2, and M3) and dividing it by the total population of people who are 21 and older.
The Federal Reserve states that in September 2001, the M1 money supply stood at 1.2 trillion dollars. While this is a little out of date, the current figure is close to this, so we'll use this measure. According to the U.S. Census Population Clock the U.S. population currently stands at 291,210,669 people. If we take the M1 money supply and divide it by the population, we find that if we divided M1 money up equally each person would get $4,123.
This doesn't completely answer your question, as you wanted to know how much money there would be per person over the age of 21. I don't know how many people over the age of 20 there are in the United States, but Infoplease reports that in the year 2000 71.4% of the population was above the age of 19. This implies that right now there are around 209,089,260 people in the United States who are 20 or older. If we split up the M1 money supply among all those people, they would each get around $5,742.
We can do the same calculations for the M2 and M3 money supplies. The Federal Reserve reports that the M2 money supply stood at $5.4 trillion in September 2001 and M3 was at $7.8 trillion. See the table on the bottom of the page to see what the per capita M2 and M3 money supplies are.
If you'd like to ask a question about the money supply or any other topic or comment on this story, please use the feedback form.
Per Capita Money Supply
|Money Supply Type||Value||Money Supply Per Person||Money Supply Per Person Over 19|
|M1 Money Supply||$1,200,000,000,000||$4,123||$5,742|
|M2 Money Supply||$5,400,000,000,000||$18,556||$25,837|
|M3 Money Supply||$7,800,000,000,000||$26,804||$37,321|