Emergency Medicine is the field of medicine designed for prevention, diagnosis, and treatment of urgent or life-threatening illness and injury. Approximately 40,000 US Emergency Department Physicians encounter nearly 4 million patients of all ages annually. Despite roots as far back as the French Revolution, EM as a board-certified medical specialty is still relatively new. Residency training in EM began at the University of Cincinnati in 1970, and has since grown to include 158 three- and four-year programs across the country. Subspecialization within the field is emerging, with fellowships available in everything from Emergency Medical Services (EMS) and Sports Medicine to Medical Education, Medical Legal, and Critical Care.