"The Office of State Treasurer administers the Unclaimed Property Division, the state’s largest lost and found. The state currently is holding more than $400 million in unclaimed assets. Each year financial institutions, businesses, government agencies and other organizations turn over millions of additional dollars and the contents of nearly 500 safe deposit boxes to the Unclaimed Property Division. Statistically, one of every 10 Missourians has assets being held by the state's Unclaimed Property Division.

...Unclaimed Property Division use a variety of resources to assist in finding the original owners or rightful heirs of unclaimed property.  The Unclaimed Property Division maintains unclaimed funds in trust for the rightful owners or their legal heirs forever.  Unclaimed property never becomes the property of the State of Missouri." (taken from the Missouri State Treasury Unclaimed Property Divison Website)

As far as States go, Missouri is very active in pursuing the return of Unclaimed Money & Property to the rightful owners.