The following rules apply to casual gamblers who aren't in the trade or business of gambling. Gambling winnings are fully taxable and you must report the income on your tax return. Gambling income includes but isn't limited to winnings from lotteries, raffles, horse races, and casinos. It includes cash winnings and the fair market value of prizes, such as cars and best online casino usa trips.
Pari-mutuel betting: North Dakota allows a primitive form of pari-mutuel betting, called Calcutta Pool, on all sporting events other than high school contests—age limit 18. North Dakota Century Code §53-06.1-07.3. North Dakota is apparently the only state to put a higher limit—minimum age 21—on pari-mutuel wagering at OTBs than at the track. The state's racing commissioners report the minimum age as being 18. Association of Racing Commissioners International, Inc., Pari-Mutuel Racing: 1996 at 59.