You have to be at least 21 years old to enter a casino and gamble in most US states, while some states allow entrance at 18 for specific activities. It is crucial to check the legal gambling age in the state you plan to visit before attempting to enter a casino. Casinos are very strict about age requirements and will ask for identification to verify your age before allowing you to enter the gaming area. Underage individuals attempting to enter a casino can face legal consequences, including fines and potential criminal charges. Always ensure you meet the minimum age requirement before planning a visit to a casino.