Indeed, bets were always recorded in a physical “book” that was kept on the premises before the game. This way, they would balance out all the bets that could cost them money and come out with a profit. The bookmaker would try to “make the book” by laying bets on every outcome that gamblers would bet on. Bets were placed over the phone and odds changed as the weight of money shifted between favorite and underdog.
Sports betting in the US was once dominated by Las Vegas sportsbooks and backroom bookmakers.
