New York mandated no ship could come within 300 yards of a dock if anyone on the ship was showing signs of cholera. However, patients were able to slip through the cracks and the disease killed 3,500 of New York City’s 250,000 residents, demonstrating the need for a formal quarantine system to be universally adopted. Following epidemics of plague and cholera that swept through Europe in the late 1840s, the first international sanitary conference was held in Paris with a focus on making quarantine an international cooperative effort. When the era of bacteriology began in 1890, major diseases such as typhoid and cholera were determined to arise from germs and not bad air or other widely held beliefs. These discoveries caused the length and nature of quarantines to evolve based on the life cycles of specific microbes instead of being based on a lack of knowledge, hysteria, and fear. In 1893, the United States Congress passed the National Quarantine Act, creating a national system of quarantine but still allowing state-run quarantines. In 1903, the New York City Department of Health opened a quarantine facility to isolate tuberculosis