1. Criminals: From fraud to kidnapping, criminals don't tell their governments amount of their annual incomes.

2. Politicians and Bureaucrats: Bribery is alive and well in world. The only country that may have keep dishonest people from government service is Singapore. When Mobutu Sese Seko left office, he had accumulated a $10 billion dollar fortune. He could have written a check and paid off Zaire's $7 Billion foreign debt. I suspect same could be said of most dictators who have been in office for years.

3. Immigrants: If they can't legally work in their adopted country, they are automatically assigned to underground economy. This is as true of Indonesians fleeing to Malaysia as it is of Hondurans fleeing to Guatemala. The best guess is that there are probably between 18-20 million undocumented workers in United States. All are members of underground economy.

4. American Citizens: In USA, you are only unemployed as long as you are drawing unemployment benefits. Thereafter, you no longer exist at U.S. Dept of Labor. In past few years, six million workers have disappeared from U.S. Dept of Labor unemployment statistics. I suspect that many have joined underground economy.

The U.S. Government estimates there are 25 million underground economy entrepreneurs. Some are homeless collecting aluminum cans and crowding day labor halls. Some are merchants at Ebay, which has 40 million merchants, who do Internet sales that aren't reported. The smarter ones take a clue from Owlhooters of 1950s and 1960s and go to a local Junior Colleges and learn marketable skills.

5. Employed Americans: Trade-persons, professionals and almost anyone with a useful skill often do side work for which they are paid in cash. Business owners often don't report all their income. Most traditional workers directly or indirectly earn unreported income. These people have one foot in traditional economy, other in underground economy.

6. Sophisticated Investors: These people, from almost every country, realize that putting all of their eggs in any one economic basket is a bad bet against future. They go offshore to their country of residence to increase investment income and reduce taxes. Governments, including United States, are anxious to recruit these investors to build their national economies. This group controls trillions of dollars of investment capital.

Whether caused by taxes, excessive regulations, ineffective law enforcement, corrupt government or bad laws, it is clear that government is prime cause of growth of underground economy. I see that growth as a piece of evidence for steady increase in probability that our children will meet Mother of All Depressions. A study of underground economy during Dark Ages might prove to be a useful manual for generations to come to come.