The legality of bookmaking varies from state to state in the US. While some states have legalized sports betting and have established regulations for licensed operators, others still prohibit it. Running an illegal bookmaking operation has severe legal consequences, including fines and imprisonment.
NCAA, 35 states plus the District of Columbia have legalized sports betting. Each of these states have established rigorous licensing regimes to ensure game integrity and consumer safety. Sportsbooks and bookies that offer sports betting outside of these licensing regimes whether in person or online are illegal.