Coin collectors might notice that there are a surprising number of $20 double eagle gold coins available on the market in very high grades. This is because at one time the major function of this denomination was to transfer value between banks. The average citizen wouldn't carry a $20 coin. Such a coin represented several weeks wages and had far too great a purchasing power to make it practical. In 1860, eleven years after the introduction of the $20 double eagle, the average wage for a six-day work week for a skilled laborer was $9.72, according to Historical Statistics of the United States, published by the U.S. Department of Commerce.

Collectors will also observe that $500 and $1,000 bank notes occasionally appear through collector markets and once in a while over the counter at banks. These are still legal tender, but the highest bank note denomination currently issued by the United States is $100. Once again, these higher denomination notes served a purpose, primarily being used for bank transfers. The value of one of these notes simply represents more money than the average person earned in a week at the time they were printed.

All this has changed in the electronic age. Today banks transfer money electronically, aided by computers. It is no longer necessary to make the physical transactions that were made in the past with either gold coins or with high denomination bank notes.

Electronic transfers are so commonplace today that any cash transaction involving $10,000 or more in coins or bank notes now requires being reported on a special form to the IRS.