In football's early years, numbers were used sporadically, but they didn’t follow a consistent system. In 1920, the Akron Pros were the first NFL team to wear numbers on their jerseys, but these were only for identification, not for the categorization we see today. It took until 1952, for the league to formally adopted a numbering system that categorized players based on position — quarterbacks wore numbers 1-19, running backs 20-49, and so on. By the 1960s, the system was solidified in the league, although it has continued to evolve.