Unclaimed or Abandoned Funds are monies which are being held by numerous agencies until the owner claims them. There are thousands of institutions that hold abandoned or unclaimed funds , but the majority of the unclaimed funds are held by state and federal agencies. Through reciprocity and streamlined reporting, assets are properly reported and placed in the custody of the state of the owner's last known address. Unclaimed property is to be returned to the state of the property owner's last known address. If there is no owner's address associated with the property, then it should be returned to the state in which the business remitting the funds is incorporated.
States regularly exchange property and related information.
This is why it is important to check all states for unclaimed money and property which may be owed to you regularly, not just the most recent state you may have resided in. No one really knows, however it is billions of dollars.