Social casinos and sweepstakes casinos are legal in every state (exceptions may apply to specific casinos) in the US with the exception of Washington, a stark contrast from regular online casinos which are only regulated in seven states–Connecticut, Delaware, Michigan, New Jersey, Pennsylvania, Nevada, and West Virginia.
At sweepstakes casinos and social casinos, you can get started playing without wagering real money. However, even if you are not placing your funds on the table, you are eligible to earn sweeps coins, gold coins, and other rewards, which you can then exchange for cash prizes.