Both great ethnic upheavals peaked with immigration at its historical maximum.

Evidence

The two great explosions of ethnic turmoil associated with immigration took place at the peak of the greatest waves of immigration in American history, one in the 1850s when several leading American cities were half foreign born, the other around World War I when firstand second-generation immigrants together reached an all-time high in proportion to the older native-born Americans. — John Higham, Strangers in the Land, 2054

Categorization

• SEED: Angle for reader: the manufactured-enemy wave crests not with absolute numbers but at the historical all-time peak proportion of newcomers — testable across eras.