Chiropractic history began in 1895 as the world was well into the second industrial revolution, marked by innovation and creativity. Health care had recently emerged from the drastic practice of heroic medicine and was well into an age of alternatives. All varieties of treatments and cures including scientific medicine, vitalism, herbalism, magnetism and leeches, lances, tinctures and patent medicines were developing and competing to be the new method for the century. Neither consumers nor many practitioners had much knowledge of either the causes of, or cures for, illnesses. Allopathy, fueled by Louis Pasteur's refutal of the centuries old spontaneous generation theory in 1859, was growing rapidly just as Charles Darwin published his book on natural selection. German bacteriologist, Robert Koch formulated his postulates bringing scientific clarity to what was a very confused field. Drugs, medicines and quack cures were becoming more prevalent and were mostly unregulated. Concerned about what he saw as the abusive nature of drugging, MD Andrew Taylor Still, ventured into magnetic healing (meaning hypnotism then) and bonesetting in 1875. He opened the American School of Osteopathy (ASO) in Kirksville, Missouri in 1892.[3] Daniel David Palmer (DD Palmer), a teacher, grocer turned magnetic healer opened his office of magnetic healing in Davenport, Iowa in 1886. After nine successful years, DD Palmer gave the first chiropractic adjustment to a deaf janitor, Harvey Lillard, on September 18, 1895.

Palmer and his patient Harvey Lillard gave differing accounts of when and how Palmer began to experiment with spinal manipulation. Palmer recalled an incident in 1895 when he was investigating the medical history of a partially deaf man, Harvey Lillard. Lillard informed Palmer that while working in a cramped area seventeen years earlier, he felt a 'pop' in his back, and had been nearly deaf ever since. Palmer’s examination found a sore lump which indicated spinal misalignment and a possible cause of Lillard's deafness. Palmer corrected the misalignment, and Lillard could then hear the wheels of the horse-drawn carts in the street below.

Palmer said "there was nothing accidental about this, as it was accomplished with an object in view, and the expected result was obtained. There was nothing 'crude" about this adjustment; it was specific so much so that no chiropractor has equaled it."

However, this version was disputed by Lillard's daughter, Valdeenia Lillard Simons. She said that her father told her that he was telling jokes to a friend in the hall outside Palmer's office and, Palmer, who had been reading, joined them. When Lillard reached the punch line, Palmer, laughing heartily, slapped Lillard on the back with the hand holding the heavy book he had been reading. A few days later, Lillard told Palmer that his hearing seemed better. Palmer then decided to explore manipulation as an expansion of his magnetic healing practice. Simons said "the compact was that if they can make [something of] it, then they both would share. But, it didn't happen."

Since DD Palmer's first claim of restoring hearing to Harvey Lillard, there has been controversy about whether a link actually could exist between the spinal adjustment and return of hearing. Critics asserted that a spinal adjustment cannot affect certain areas - like the brain - because the spinal nerves do not extend into the encephalon. Years later, V. Strang, D.C. illustrated several neurological explanations including the recognition that sympathetic nerves arising in the lateral horns of the upper thoracic levels of the spine form the upper cervical ganglion with postganglionic fibers ascending to supply, among other things, blood vessels of the brain.