In what decade were Ten Codes developed by law enforcement?

The Ten Codes, also known as Police Codes or Ten Signals, were developed in the 1930s to facilitate communication among law enforcement personnel. During this decade, police departments began seeking more standardized methods of radio communication to improve clarity and efficiency in the field. The codes served to create concise, easily understood shorthand for common situations, thus minimizing misunderstandings and enhancing the efficiency of communication during police operations. This development coincided with advancements in radio technology, which allowed for broader and more effective communication between officers. The introduction of these codes laid the groundwork for their widespread usage in police communication throughout later decades.