Hi, P.
As a very junior auditor nearly 50 years ago, one of my first audits was of a small bank in Oklahoma. A standard auditing technique then (and maybe still) was to confirm a sample of deposit accounts, especially dormant accounts. That is, we would mail a letter to the depositor asking him/her to confirm to us that, yes, that account was theirs and that the amount agreed with their own records. Most of the replies were routine, but one was from an elderly lady who said, "Thank you for reminding me. I forgot that I had that money in there!" That savings account had not been touched - except by interest added - for several years. The balance was about $14,000 - and that was in 1960!
It was several years later that I first heard the word "escheat". As someone else said, it was common for banks to levy a monthly or other periodic surcharge on dormant accounts; given a long enough time, this would eventually wipe out the balance in most accounts, eliminating the "dormant account problem".
Every year, the controller or treasurer or other official of most states publishes a list of "unclaimed accounts". These are assets that have escheated to the state because the owners cannot be located. The bank or other holder is not allowed to simply expropriate the asset, but must turn it over to the state, which will hold it until the owner can be located and identified and can claim the property. When I lived in California, we were amused that the state officials were unable to locate Bob Hope, Doris Day and several other well-known owners of such accounts. Here in Texas, each year's list usually includes several prominent citizens.
One more anecdote on this subject: When we moved from California in 1080, we closed our bank accounts there, but a miscalculation by the Bank of America left us with one cent in my wife's checking account. For several months, she continued to get the monthly statement showing that penny balance. Finally, BofA sent her a Cashier's Check for $0.01 to close the account. She was too embarrassed to ask some teller to cash that small check, so I did it for her. Having been on the other side of the desk, I did not want that account to show up on the bank's list every month for years - and some poor clerk have to reconcile it.
RC