By the last years of the 19th century, anti-Asian propaganda shifted gears to new threats. During and after the Spanish and then Philippine-American War of 1898-1902, there was a great deal of debate whether to take on colonies. Much of the anti-imperialist side relied on white supremacy to make their case, fearing the infection of tropical peoples into the white man's nation.
Here is a prime example, with the savage Filipino attacking Congress who is presenting them with civilization. Probably from 1898, but I don't have an exact date.