By the turn of the 20th century, horseless carriages were becoming more common on public roads, prompting debates about safety, taxation, and law enforcement. Prior to standardized plates, many drivers displayed owner-provided identifiers—paper, leather, or painted numbers—making enforcement inconsistent. In 1903, authorities in some U.S. states and municipalities moved to formalize identification by issuing the first modern-style license plates: government-produced, durable tags bearing assigned registration numbers. The new plates served multiple purposes. They allowed police to link vehicles to owners, helped impose road taxes and fees, and provided a visible means to enforce emerging traffic rules. Early plates were simple—typically stamped metal, sometimes enamel-coated, showing a number and often the issuing jurisdiction and year. Production methods and materials varied: brass, leather-backed metal, and porcelain surfaced in different places. Designs changed rapidly in subsequent years as states and countries refined registration systems and anti-counterfeiting measures. Historical evidence shows that registration laws and issuance of plates did not spring from a single nationwide law but from a patchwork of local and state actions responding to growing vehicle use. For example, New York required registration beginning in 1901 but initially issued only registration numbers for owners to display on their vehicles, often on homemade plates; by the early 1900s many jurisdictions shifted to issuing standardized metal plates. The process of adopting plates reflects broader trends: urbanization, reliance on automobiles for commerce, and the professionalization of policing and road oversight. Although 1903 is widely cited as a pivotal year in the adoption of government-issued license plates, the historical record is nuanced. Different jurisdictions reached the same outcome at different times, and surviving artifacts and municipal records show variation in exact dates, materials, and legal language. Scholars and collectors rely on state statutes, city ordinances, and archived registration logs to trace the evolution of motor vehicle identification. The introduction of official plates was a practical response to new technology rather than a single dramatic event. Over the next decades, nations around the world adopted similar systems, standardizing sizes, introducing renewal stickers, and later incorporating reflective materials and alphanumeric schemes to handle growing vehicle fleets. Today’s license plates are direct descendants of those early 20th-century tags: government-issued identifiers intended to associate a vehicle with its legal owner and to support public safety and administration. Sources for this summary include contemporaneous state and municipal registration laws, surviving early plates in museum and private collections, and secondary histories of automotive regulation. Because adoption was staggered and records vary by jurisdiction, precise first-use claims are sometimes disputed; statements here rely on the consensus view that the early 1900s—around 1903—marked the widespread shift to government-issued metal license plates.