You have to be at least 21 years old to gamble at most casinos in the United States. This age requirement is strictly enforced to ensure compliance with gambling laws. Minors are not allowed to participate in any form of gambling activities, including casino games and betting. Age verification is commonly done through identification checks at the entrance or during cash transactions. It is important to adhere to these age restrictions to avoid legal consequences and protect young individuals from the risks associated with gambling. Remember, always gamble responsibly and within the legal age limits.