Medicaid was originally designed to provide health coverage to low-income elders, people with disabilities, and families with children receiving cash welfare, but has evolved to assume responsibility for many more people who fall through the cracks of private insurance coverage as a result of the U.S. health care system.  Indeed, the program has been likened to the "tail of the line" at the end of a fast moving children’s game of crack the whip, absorbing the changes in coverage created by other institutions and phenomena that lead the line (Mann and Westmoreland 2004).