The Morongo Casino in Cabazon California has an age limit of 18. Some tribal casinos are 18, some 21 - it's up to the individual tribe and the state government.
These age limits are set by the states, but every state requires that you be 21. Other countries and cruise ships in international waters have different rules, however.
In the United States, there is not. However, in Canada, the legal age to game is 19, so you can go there (in Ontario, there are three, located in Orillia, Niagara Falls and Windsor).
