Early roots of the current hospital system can be traced back to the 1800s with the development of almshouses, which were developed to serve primarily the poor population. Since then, major milestones and accomplishments have been instrumental in forming today’s system. These major milestones are divided into four sectors and, according to Niles, the milestones for each provide an introduction as to how each sector has evolved to form part of the U.S. healthcare system.