The line formed at the Borgata casino well before 11 a.m., the designated time that sports betting was set to begin on Thursday. There were a few gamblers who were prepared to wager thousands of dollars, and many others who wanted to make bets that were much more modest, arriving simply to be part of a moment that felt historic.

Scott Cronick was among the first to make it to the betting window, following state officials and Julius Erving, the retired basketball player, in placing some of the first legal bets on sporting events in New Jersey. He bet that the Yankees would win the World Series, the 76ers would claim the N.B.A. title and the Cowboys would be the Super Bowl champions.

“I made a lot of dumb bets today as a fan,” said Mr. Cronick, a radio broadcaster from nearby Somers Point. “I’ll make smarter bets as we go on.”