A woman from Texas has become the first United States resident to die from swine flu.
Health officials say she had chronic underlying health conditions.
The only other person to die from the H1N1 virus outside Mexico has been a Mexican child, agged 22 months, who died in Texas on 27 April.
The Centers for Disease Control and Prevention said on Tuesday the United States now has 403 confirmed cases of the new H1N1 flu, in 38 states.
The official global swine flu death toll now stands at 31, although dozens more deaths in Mexico have been linked to the virus.