The game's trajectory changed when a Catholic priest from Wilkes-Barre, Pennsylvania, approached Lowe about using bingo for church fundraising. The problem was immediate: with too few unique cards, multiple players won simultaneously, splitting prizes and reducing the fundraising yield. Lowe hired Carl Leffler, a Columbia University mathematics professor, to generate thousands of unique card combinations. Leffler eventually produced over 6,000 distinct cards, each with a unique number arrangement. The work reportedly drove him to a breakdown.
The expanded card set made large-scale bingo viable, and churches adopted it rapidly. By 1934, an estimated 10,000 bingo games were played weekly across North America. The game had become one of the most effective community fundraising tools of the Depression era, a role it continues to serve in many communities today.