Yellow fever known as "mosquito inspectors" fiercely worked to combat yellow fever throughout Rio by spraying, exterminating rats, improving drainage, and destroying unsanitary housing. Ultimately, the city's sanitation and renovation campaigns reshaped Rio de Janeiro's neighborhoods. Its poor residents were pushed from city centers to Rio's suburbs, or to towns found in the outskirts of the city. In later years, Rio's most impoverished inhabitants would come to reside in "favelas". During 1920–23, the Rockefeller Foundation’s International Health Board undertook an expensive and successful yellow fever eradication campaign in Mexico. The IHB gained the respect of Mexico’s federal government because of the success.
Yellow fever the Louisiana Purchase to the US in 1803. In 1804, Haiti proclaimed its independence as the second republic in the Western Hemisphere. The yellow fever epidemic of 1793 in Philadelphia, which was then the capital of the United States, resulted in the deaths of several thousand people, more than 9% of the population. The national government fled the city, including President George Washington. Additional yellow fever epidemics struck Philadelphia, Baltimore, and New York City in the 18th and 19th centuries, and traveled along steamboat routes from New Orleans. They caused some 100,000–150,000 deaths in total. In 1853, Cloutierville, Louisiana, had