Chapter 20: Early Adoption - The Automotive Industry |
In the late 1970s, General Motors used Code 39 to track subassemblies on production lines, replacing handwritten logs. This seemingly modest change represented a watershed moment---not just for GM or for barcode technology, but for the entire paradigm of industrial automation. To understand why this adoption was so significant, and why Code 39 became the linchpin of automotive tracking for decades, we must first understand the symbology itself. |
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A Brief Technical Profile of Code 39 |
Code 39, also known as Code 3 of 9, was developed in 1974 by Dr. David Allais and Ray Stevens of Intermec Corporation . It was a revolutionary step in automatic identification because it was the first barcode symbology capable of encoding not just numbers, but the full alphanumeric character set---uppercase letters A through Z, digits 0 through 9, and a handful of special characters like the hyphen, period, space, dollar sign, slash, plus sign, and percent sign . This expanded character set was critical for an industry like automotive manufacturing, where part numbers and assembly instructions are rarely purely numeric. |
The technical underpinnings of Code 39 are elegant in their simplicity. Each character in the code is represented by a pattern of nine elements: five bars and four spaces. Crucially, three of these nine elements are wide, and six are narrow---hence the name 'Code 3 of 9' . This pattern, known as a 'two-out-of-five' encoding scheme for the bars, creates a unique signature for each character. |
One of Code 39's most celebrated features is its self-checking property. Because each character has a specific, asymmetric pattern of wide and narrow elements, a single printing defect---say, a bar that prints slightly too wide---cannot accidentally transform one valid character into another . The decoder will either read the intended character correctly or reject it as invalid. This built-in error detection meant that Code 39 did not *require* a mandatory check digit, though optional modulo 43 checksums could be added for an extra layer of security . |
However, this robustness came at a cost: data density. Code 39 is a low-density barcode. Because it requires space for both the start/stop characters (the asterisk, `*`), the inter-character gaps, and the wide elements that make it so reliable, it takes up significantly more space than later symbologies like Code 128 . In the automotive industry of the 1970s and 80s, this was a manageable trade-off, as parts and subassemblies were large enough to accommodate the labels, and the reliability was paramount. |
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The General Motors Proof of Concept |
In the late 1970s, the American automotive industry was in a state of flux. Facing increasing competition and a growing awareness of quality control issues, manufacturers were looking for ways to streamline operations and reduce errors. At General Motors, the production line was a marvel of engineering and human labor, but it was also a source of immense paperwork and logistical headaches. |
Before barcodes, tracking a subassembly---an engine block, a transmission, or a dashboard---through the massive GM production facilities was a manual, error-prone process. Workers would record the movement of these heavy, complex components using handwritten logs. These logs were difficult to read, impossible to update in real-time, and offered little in the way of systematic data analysis. A subassembly might be misrouted, a step in its assembly might be missed, or a defect might be traced back to a specific batch of parts only after hours or days of digging through paper records. |
This was the environment into which Code 39 was introduced. GM began using Code 39 to track these subassemblies, affixing labels that contained a unique identifier for each major component . When a subassembly arrived at a workstation, a worker would scan the label. The system would instantly identify the part, verify it was at the correct station, record the time, and perhaps even access its manufacturing history. If a part needed a specific variant of a bolt or a particular wiring harness, the scan would ensure the right components were dispatched to that station. |
This initial adoption was a proof of concept, demonstrating that barcodes could survive the harsh, dirty, and demanding environment of a factory floor. The Code 39 labels, printed on durable materials, could withstand oil, grease, and temperature fluctuations, and the scanning equipment of the time proved reliable enough for the task. The elimination of handwritten logs alone was a victory, but the real benefit was the data. For the first time, GM could track the flow of subassemblies in real-time, identify bottlenecks, and build a digital record of each vehicle's components. |
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The Automotive Industry Action Group and Standardization |
GM's internal success created a ripple effect. Other automakers, including Ford and Chrysler, were facing similar challenges and were keenly observing these developments. The need for a common standard across the industry became obvious. If GM used Code 39 for its parts, and Ford used something else, suppliers would have to maintain multiple labeling systems, creating chaos and cost. |
This realization led to the formation of the Automotive Industry Action Group (AIAG) in 1981 . Initially an exploratory committee under the American Production and Inventory Control Society, AIAG was formally incorporated in 1982 by American Motors, Chrysler, Ford, General Motors, and Volkswagen of America . Their mission was to improve quality and promote efficient processes through global standards development. By 1984, AIAG had made a critical decision that would shape the industry for decades: they adopted Code 39 as the primary alphanumeric barcode symbology for their standards . |
That same year, AIAG published its first industry-wide barcode standards: AIAG B-1 Bar Code Symbology Standard and AIAG B-3 Shipping/Parts Identification Label Standard . This standardization was a monumental step. It meant that any supplier selling parts to any of the major US automakers could use a single, standardized labeling system. The B-1 standard specified exactly how the Code 39 barcode should be printed, the size and placement of the labels, and the quality requirements. The B-3 standard detailed what information needed to be encoded, typically including the part number, quantity, supplier identification, and serial numbers . |
The adoption of the AIAG standards effectively made Code 39 the lingua franca of the North American automotive supply chain. It was no longer a convenient internal tool; it was a mandatory requirement for doing business. This drove widespread adoption among thousands of first-tier, second-tier, and third-tier suppliers. In Europe, a similar organization called Odette International set standards for the European automakers, and in Japan, the Japan Automobile Manufacturers Association (JAMA) performed a comparable role . While not all used Code 39 exclusively, the influence of the AIAG standard was global. |
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The LOGMARS Connection and Military Influence |
The automotive industry's embrace of Code 39 was not an isolated phenomenon. Around the same time, the United States Department of Defense was working on its own massive standardization project: LOGMARS, which stands for Logistics Applications of Automated Marking and Reading Symbols. The military needed a way to track the millions of parts, supplies, and equipment moving through its vast logistics network. They, too, settled on Code 39, requiring it on all inbound materials . |
The LOGMARS requirement had a powerful legitimizing effect. The U.S. military's stamp of approval validated Code 39 as a robust, reliable, and secure symbology for mission-critical applications . It provided a powerful counterargument to any executive who might question the wisdom of investing in this new technology. As Dr. David Allais himself noted, the military's standardization on Code 39 paved the way for its rapid adoption by the automotive industry . |
This dual validation---from both the military and the automotive giants---created a virtuous cycle. The demand from these two massive sectors drove down the cost of barcode scanners and printers, making them more accessible to smaller suppliers. It also spurred the development of more durable and reliable equipment, further cementing Code 39's role as the go-to symbology for heavy industry. |
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How Technical Characteristics Enabled Automotive Adoption |
The success of Code 39 in the automotive industry can be directly linked to several of its technical characteristics. |
Alphanumeric Capability |
The first and most obvious advantage was its ability to encode letters and numbers. Automotive part numbers are famously alphanumeric. A typical part number might be something like 'E3TZ-7A247-A.' Before Code 39, barcodes were largely numeric, limited to encoding a simple product identifier. Code 39 could encode the entire part number, the supplier's name, and a variety of other information directly on the label. This eliminated the need for a separate lookup table or a manual data entry step to translate a numeric code into a meaningful part identifier. |
Robustness and the Self-Checking Property |
The factory floor is an unforgiving environment. Labels get scratched, smudged with oil, exposed to heat and cold, and handled repeatedly. The self-checking property of Code 39 was not just a theoretical feature; it was a practical necessity. It meant that even if a label was slightly damaged, it could still be scanned and decoded accurately, or it would be rejected as unreadable, prompting the operator to scan it again. This drastically reduced the risk of misidentification, which in a manufacturing context could lead to costly assembly errors or safety recalls. It was this reliability that made the technology practical for tracking heavy subassemblies moving through a plant. |
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Lack of a Mandatory Check Digit |
While the absence of a mandatory check digit is often cited as a drawback of Code 39, in the early days of adoption, it was actually a significant advantage. As the Wikipedia entry notes, 'since there is no need to generate a check digit, it can easily be integrated into an existing printing system by adding a barcode font to the system or printer and then printing the raw data in that font' . |
This ease of implementation was critical for rapid adoption. Suppliers didn't need specialized software to calculate check digits; they could simply print the part number in a Code 39 barcode font. This made it incredibly easy for even small shops with basic computer systems to start producing compliant labels. The optional nature of the check digit also allowed for flexibility. If an application demanded maximum accuracy, a Modulo 43 check digit could be added. But for basic part identification and tracking, the self-checking property was often sufficient. |
Widespread Reader Compatibility |
The decision by AIAG and the military to adopt Code 39 ensured that it would be supported by virtually every barcode scanner manufacturer. It became the baseline symbology that all scanners had to decode. This universality meant that a supplier didn't need to worry about whether their customer's scanners could read their labels. This low barrier to adoption was a key driver of its widespread implementation. |
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Expanding Use Cases Within Automotive |
Once Code 39 became the established standard, its applications within the automotive industry proliferated far beyond the initial tracking of subassemblies. |
Work-in-Process Tracking |
The most common application was tracking work-in-process (WIP). As we saw with the GM example, Code 39 labels were used to track the progress of parts and assemblies through every stage of production. Scanning a label at a workstation would log the part's arrival, initiate a specific task, and record its completion. This provided real-time visibility into the status of every order on the shop floor, allowing managers to identify bottlenecks and optimize workflow. |
Shipping and Receiving |
AIAG's B-3 standard specifically addressed shipping and parts identification labels . When a supplier shipped a batch of parts to an automaker, the shipping label would contain a Code 39 barcode encoding the part number, quantity, and purchase order details. Upon arrival at the automaker's receiving dock, the label would be scanned, automatically updating the inventory system and triggering the payment process. This automated data entry drastically reduced errors and sped up the receiving process, eliminating the need for workers to manually count and record thousands of parts. |
Quality Control and Traceability |
One of the most powerful applications was in quality control and traceability. By encoding a batch number or serial number into the Code 39 label, automakers could trace a specific component back to its raw materials, its manufacturing date, and its specific production line. In the event of a quality issue or a recall, this traceability was invaluable. Instead of recalling an entire model year of vehicles, the automaker could identify exactly which vehicles contained the faulty component, saving immense time and money. |
Inventory Management |
Code 39 was also used for inventory management within the automakers' massive parts warehouses. Every bin, pallet, and container could be labeled with a Code 39 barcode. When parts were moved, taken for production, or returned, the labels were scanned, keeping the inventory system accurate in real time. This provided a level of inventory accuracy that was impossible to achieve with manual, paper-based systems. |
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Real-World Application: The SEW-Eurodrive DriveTag Example |
To understand the enduring legacy of Code 39 in the industrial and automotive sectors, we can look at a modern example: the DriveTag system from SEW-Eurodrive, launched in the U.S. in late 2025. SEW-Eurodrive is a global leader in drive automation and motion technology---the kind of sophisticated motors and gearboxes used in automotive assembly lines and countless other industrial applications. |
Their DriveTag system is a customized barcode labeling service designed to simplify product identification, streamline logistics, and optimize material flow . What is striking is that among the multiple barcode formats they offer---including DataMatrix, Code 128, and PDF417---Code 39 is explicitly listed as an option . |
Why would a cutting-edge technology company in 2025 still offer Code 39The answer lies in the very history we have just described. Many of SEW-Eurodrive's customers are automotive manufacturers and their suppliers who have been using Code 39 for decades. Their internal enterprise resource planning (ERP) systems, inventory management software, and scanning infrastructure are all built around Code 39 . Changing to a more modern symbology would require a massive, expensive, and disruptive overhaul of their entire system. |
As the DriveTag example shows, Code 39 is not just a historical curiosity. It is a living standard, deeply embedded in the digital and physical infrastructure of the automotive industry. Its continued availability ensures backward compatibility, allowing new products to seamlessly integrate into decades-old supply chains without interruption. |
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The Influence on Later Symbologies |
The widespread adoption of Code 39 in the automotive and military sectors also created the market conditions for the development of more advanced symbologies. The limitations of Code 39---its low data density and lack of native support for lowercase letters---were well understood. However, the success of Code 39 proved that there was a massive market demand for alphanumeric barcodes. |
This demand directly led to the development of Code 128 in 1981. Code 128 offered higher data density, support for all 128 ASCII characters, and a mandatory check digit, making it more efficient and secure . Today, Code 128 is often the preferred choice for new implementations where space is a premium. However, the immense install base of Code 39, particularly in industries like automotive, means it remains a viable and supported standard. |
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A Detailed Summary: The Legacy of Code 39 in Automotive |
The story of Code 39 in the automotive industry is a quintessential example of how a technological innovation can reshape an entire sector. |
It began with a practical problem: the need to move beyond error-prone handwritten logs for tracking subassemblies. General Motors' use of Code 39 in the late 1970s was not a grand, top-down strategy; it was a grassroots solution to a specific, painful operational inefficiency. This initial success provided the proof of concept. |
The creation of the AIAG and its subsequent standardization on Code 39 was the catalyst that turned a promising tool into an industry mandate. By choosing a symbology that was already validated by the U.S. military through LOGMARS, the AIAG provided a clear, unambiguous path for suppliers . |
This standardization was enabled by Code 39's key technical characteristics: |
Alphanumeric support: It could encode the complex, letter-and-number part numbers common in automotive manufacturing. |
Self-checking property: Its built-in error detection was essential for reliable scanning in the harsh factory environment. |
Ease of implementation: The lack of a mandatory check digit allowed for rapid, low-cost adoption by thousands of suppliers using simple barcode fonts. |
Universal scanner compatibility: Guaranteeing that labels could be read by any standard scanner, regardless of manufacturer. |
These characteristics, in turn, enabled a wide range of applications that drove significant business value: real-time work-in-process tracking, error-free shipping and receiving, detailed quality control and traceability, and accurate inventory management. |
The legacy of Code 39 in the automotive industry is not that it was the 'best' or most 'advanced' barcode. It was the *right* barcode at the *right* time. It provided a robust, reliable, and easy-to-implement solution that was good enough to meet the industry's needs and simple enough to be adopted by thousands of suppliers. |
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Its lasting impact is evidenced by its continued use today, as seen in systems like SEW-Eurodrive's DriveTag, which includes Code 39 as an option to maintain compatibility with established customers. The decision to adopt Code 39 in the 1980s created an infrastructure so vast and deeply integrated that it is still a part of the automotive landscape decades later. The 'iconic Code 3 of 9' therefore occupies a unique place in industrial history: a standard that built the bridge from the paper-based industrial era to the age of digital automation, one wide bar and narrow space at a time. |
cs@easiersoft.com