"United States Code
TITLE 18 - CRIMES AND CRIMINAL PROCEDURE
PART I - CRIMES
CHAPTER 17 - COINS AND CURRENCY
§ 333. Mutilation of national bank obligations

Whoever mutilates, cuts, defaces, disfigures, or perforates, or
unites or cements together, or does any other thing to any bank bill,
draft, note, or other evidence of debt issued by any national banking
association, or Federal Reserve bank, or the Federal Reserve System,
with intent to render such bank bill, draft, note, or other evidence
of debt unfit to be reissued, shall be fined under this title or
imprisoned not more than six months, or both."

The key word in the US Code is "Intent". The "Intent" of Where's George? is keep bills in circulations and have others re-enter them (a hit to WG participants) in order to track the bills travels. The longer the bill stays in circulation the better. Therefore WG is not a violation of the US Code since the intent is not to make the bill "unfit". The Secret Service visited the website owner shortly after the site became operational about 11 1/2 years ago. After a review & discussion the Secret Service said WG was not illegal & allowed WG to continue.