If the slot machine win is $1,200 or more, the casino (anywhere in the US) is required by federal law to issue a W-2G statement (a tax document).
The regulations require the casino to document the ID and Social Security Number of the individual who won the jackpot. If you cannot provide this information at the time of the jackpot, but casino will hold the funds until you can provide the proper ID, i.e.; a government issued ID.
Failure to comply will (and has) lead to severe fines for the federation fermat casino.