2009 swine flu pandemic in the United States by state

The United States experienced the beginnings of a pandemic of a novel strain of the influenza A/H1N1 virus, commonly referred to as "swine flu", in the spring of 2009. The earliest reported cases in the US began appearing in late March 2009 in California, then spreading to infect people in Texas, New York, and other states by mid-April. Early cases were associated with recent travel to Mexico; many were students who had traveled to Mexico for Spring Break. This spread continued across the country's population and by the end of May there were approximately 0 confirmed cases throughout all 50 states.

On April 28, 2009, the director of the Centers for Disease Control and Prevention (CDC) confirmed the first official US death of swine flu, a 23-month-old toddler from Mexico who died on April 27 while visiting Texas. By June 24, 132 deaths had been attributed to the virus. As of January 11, 2010, at least 554,000 deaths were attributed to the virus worldwide, and at least 12,469 deaths in the US were confirmed to be due to the virus. The CDC suspects, however, that the total number of deaths in the US is much higher than the official total, as some deaths probably went unconfirmed.