New scientific knowledge helped the building of the Panama Canal, as fewer workers got sick from malaria and yellow fever.
The discovery that yellow fever was transmitted by mosquitoes was made in 1891, but most sanitary officials didn't know or didn't give relevance to it.
However, captain William Gorgas did know about this and successfully helped to eradicate yellow fever and malaria in the Canal Zone, despite the opposition from U.S. officials who wanted to discredit his work.
President Theodore Roosevelt supported Gorgas and the Panama Canal was completed by 1914.