Myth:
It is illegal to place a bet in the United States.

Fact:
This is not true in the majority of states. There is no federal law which criminalizes the placement of a bet by a bettor. This holds true in the majority of states; although there are a some states which do criminalize state-sanctioned betting. Americans make up more than one-half of all Internet gamblers. With the millions of Americans playing online for the past ten years, there has been only one reported prosecution of an online bettor, and his circumstances were so unique that his case is not representative of any prosecution trend or practice.

References:
I. Nelson Rose and Martin D. Owens, Internet Gambling Law (Mary Ann Leibert, Inc., 2005), pp. 3, 36 (“Federal law is clear. The federal government’s interest in gambling is pretty much limited to organized crime. Federal statutes are written with phrases like, “Whoever being engaged in the business of betting or wagering. . .” or “Whoever conducts, finances, manages, supervises, directs, or owns all or part of an illegal gambling business. . .” ) and p. 37 (about half of the states criminalize wagering under certain circumstances, “even though nobody is ever charged any more.”)