Last updated October 17, 2026

The History of Medical Coding Timeline

The History of Medical Coding

By By Janine Mothershed

The history of medical coding stretches back more than 350 years. Long before computers and claim forms, people looked for ways to track disease and causes of death. Today, those early efforts have grown into the detailed code sets that medical coders use every day.

The Early History of Medical Coding

One of the earliest examples comes from London’s Bills of Mortality. These weekly reports listed deaths and their causes in the city. In 1662, John Graunt studied the Bills and used them to find patterns in disease and death. As a result, many historians call his work the beginning of modern health statistics.

During the Great Plague of 1665 and 1666, the Bills became even more important. They showed how fast the plague spread through London. However, clerks did not record causes of death in a consistent way, so the data had limits.

Building a Classification System

In the 1830s and 1840s, Dr. William Farr, a British epidemiologist, pushed for a uniform system to classify causes of death. Later, in 1893, Jacques Bertillon presented the International List of Causes of Death. Countries around the world adopted it and revised it about every ten years.

In 1948, the newly formed World Health Organization (WHO) took over the list. At that point, it became the International Classification of Diseases (ICD), and it began to include illnesses as well as causes of death. For the first time, doctors and researchers could compare health data across countries.

Medical Coding in the United States

In the United States, providers began using codes for billing and payment. For example, the American Medical Association first published CPT in 1966 to describe procedures and services. Later, Medicare adopted HCPCS to cover supplies, drugs, and other items.

For many years, coders worked from paper records and printed code books. In the 1980s, coders still wrote much of their work by hand or on a typewriter. Over time, however, electronic health records and coding software changed the job.

The United States moved from ICD-9-CM to ICD-10-CM on October 1, 2015. The new code set is far more specific than the old one. In particular, it captures laterality, severity, and anatomy in much greater detail. As a result, payers receive more accurate data for reimbursement and quality reporting.

Medical Coding Today

Today, ICD-10-CM contains more than 70,000 diagnosis codes, and it updates every October. Medical codes support claims, coverage decisions, and public health research. In addition, health plans such as Medicare and Medicaid rely on them to track disease and plan care.

Technology has also changed where coders work. Most records now move electronically, so many coders work remotely. In short, the history of medical coding shows a field that keeps growing and changing.

If you want to become part of this important field, Coding Clarified homepage about our program and contact us today. The future of medical coding looks bright.

Ready to become a certified medical coder? Our online CPC certification training prepares you for the AAPC CPC exam with a credentialed instructor. Many students train at little or no cost through medical coding scholarships and WIOA grants available in 30+ states.

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