The US opioid epidemic represents one of the most catastrophic public health crises in recent history, evolving over three decades and distinct waves. This chapter examines how what began as a prescription drug crisis—driven largely by the aggressive marketing of OxyContin—transformed into an epidemic of heroin use and ultimately a crisis dominated by illegally manufactured fentanyl. The geographic progression of the epidemic from rural Appalachia to a nationwide crisis is mapped alongside changing demographic patterns that have increasingly affected minority populations and women. By analyzing prescribing patterns, overdose rates, and policy responses, this chapter reveals how attempts to address one aspect of the crisis often led to an inadvertent worsening of other aspects. The devastating impact of the epidemic is quantified not only in terms of mortality—with recent data showing approximately 200 deaths per day from fentanyl alone—but also through its profound effects on communities, healthcare systems, and vulnerable populations, including women and children.