My customer at one time was the NY Federal Reserve bank. I had a tour of the cash vault just prior to the millennium. The cash vault is like a furniture warehouse, there are floor to ceiling stacked shelves with pallets of cash. Each pallet has 250,000 bills, so a pallet of $100's is $25 million. They were prepared for a run on cash as it was widely believed that all the computers were expected to shut down at midnight on New Years. I was told that there was $70 billion in the vault at the time.