Three spinning reels and a small selection of symbols, such as playing cards, horseshoes, and the Liberty Bell, were included in this straightforward machine. In the United States, the demand for more captivating and eye-catching macirish slotshines increased along with the popularity of gambling. By the 1930s, slot machine design had changed due to the addition of fruit symbols, such as lemons & cherries, which eventually led to the 777 symbol becoming a symbol for jackpot wins. The design & operation of slot machines evolved along with technology. A major turning point was reached in the 1960s with the introduction of electromechanical slots, which enabled more intricate gameplay and larger payouts.