Online casinos are legal in specific US states. These are; New Jersey, Delaware, Michigan, Pennsylvania, and West Virginia. You don't necessarily need to live in one of these states to gamble online, but you need to be physically within the state lines. So if you live in New York but are on a trip to New Jersey, you are free to use online casinos during your stay. State laws change frequently, and we expect more parts of the US to legalize online gambling soon.