> Are you telling me that the government forgot to collect the serial numbers of every dollar bill as it enters the banking system? They do. Mainly to track b

> Are you telling me that the government forgot to collect the serial numbers of every dollar bill as it enters the banking system? They do. Mainly to track banknote usage and average life from when / where they enter circulation, to when / where they end up. Basically demand for and lifecycle of cash. It is valuable information for knowing how much to print, and for improving the durability of notes themselves (which is surprisingly low, an average of months, with a non-fat long-tail to weeks, for low denomination notes). [BTW, the date on the note has little to no relationship to the date it enters circulation, the serial number is used for this.]