The Media feeds on it.
Millions of patients love their chiropractor and appreciate our unique and safe approach to recovery from pain. Significant research suggests that chiropractic is the safest approach available for relief from neck pain, back pain, headaches and other “musculo–skeletal” complaints. Lets review that research, and discuss how Organized Medicine has contributed to the myth that chiropractic care is dangerous.
First, a short review of history
In the early 1960's, the American Medical Association (AMA) decided to try to contain and eliminate Chiropractic as a profession. 
The AMA's plan was to:
prevent medical physicians from referring patients to Chiropractors,
and preventing them from accepting referrals from Chiropractors;
preventing Chiropractors from obtaining access to hospital diagnostic and radiology services;
preventing medical physicians from teaching at chiropractic colleges,
or engaging in any form of joint research;
and, to stifle any other form of cooperation between the two professions.
Medical journals were also told not to publish any chiropractic research, unless
the results were nehative. This persisted until the late 1990s.
The AMA also told its membership, medical students, insurance companies, and the general public that Chiropractic was an “unscientific cult”.
In 1976, five Chiropractors filed a lawsuit against the AMA and 20 other medical specialty organizations as co-conspirators, for violation of the Sherman Anti-trust Laws. After 15 years of litigation, the U.S. Court of Appeals stated that the AMA intended to “destroy a competitor,” and that there was evidence “showing that the AMA was motivated by economic concerns”. The court found that the AMA had concealed evidence showing it's guilt, and was caught “doctoring” documents. The AMA was also “guilty of systematic, long term wrong doing and has not acknowledged its lawlessness”. 
Following the Court enforced reversal of AMA's policy, tiny splinter groups formed, with the intention of labeling chiropractic as a quackish cult. Their methods mimicked the earlier AMA suppression tactics: Create doubt about the quality of chiropractic education, and mislead the public into believing that chiropractic claims ALL disease is caused by subluxations. Although these groups hide behind the noble claim that they wish to protect the public from unscientific practices, their true motives are transparent. Their sole intention is to suggest that only allopathic medicine is well supported by scientific research. However, that is just not true!
In an editorial in the highly esteemed British Medical Journal, titled
Where is the Wisdom? The Poverty of Medical Evidence, BMJ's editor Dr. Richard Smith recounts a lecture he attended with renowned health policy consultant Dr. David Eddy. Eddy found, after doing significant research, that only about 13% of medical interventions are supported by, solid scientific evidence and that only 1% of the articles in medical journals are scientifically sound. Why is that? Because most of those articles quote from other articles which make unsupported and unfounded claims.
The Increasing Popularity of Alternative Medicine
After publication of David M. Eisenberg's 1993 New England Journal of Medicine article, titled
Unconventional Medicine in the United States, various factions of organized medicine became increasingly anxious, and aggressive in their accusations that alternative approaches to medical healthcare were not supported by research. 
That same group was hardly forthcoming in mentioning the small fraction of established medical practices that had ever met those same stringent requirements. They certainly never mention the low level of success which medicine delivers for the same health complaints for which chiropractic has become famous.