Since the first US case of coronavirus disease 2019 (COVID-19) infection as identified in Washington State on January 20, 2020, more than 235 000 cases have been identified across the US in just over 2 months. Given the challenges in expanding testing capacity and the restrictive case definition of persons under investigation, the true number of cases is likely much higher.

By March 17, the outbreak had expanded from several isolated clusters in Washington, New York, and California to all 50 states and the District of Columbia. As of April 2, there have been more than 5000 COVID-19–associated deaths in the US. With a global total now of more than 1 million cases, the US is now the country with the largest number of reported cases, comprising about one-fifth of all reported infections.

With community transmission firmly established, the US epidemic enters the exponential growth phase in which the number of new cases is proportional to the existing number of cases. This phase continues until either enough susceptible individuals become immune as a result of infection, stringent public health measures are followed, or both.

自2020年1月20日在华盛顿州确认美国首例冠状病毒病2019（COVID-19）感染以来，仅在短短两个多月的时间里，美国就发现了超过235 000例病例。鉴于在扩展测试能力方面面临的挑战以及受调查人员的限制性案件定义，案件的真实数量可能要高得多。

到3月17日，疫情已从华盛顿，纽约和加利福尼亚的几个孤立集群扩展到所有50个州和哥伦比亚特区。截至4月2日，在美国已有超过5000例与COVID-19相关的死亡。目前，美国的全球总病例数超过100万，是报告病例数最多的国家，约占报告的所有感染病例的五分之一。

随着社区传播的牢固建立，美国流行病进入了指数增长阶段，在该阶段，新病例数与现有病例数成正比。这个阶段一直持续到有足够的易感个体由于感染而变得免疫，采取严格的公共卫生措施或两者兼而有之为止。