Blanqueamiento aka racial whitening was a law written to dilute the "negro problem". European immigrants were funded by the state & federal to travel in & impregnate women towards the white ideal.
Afterward, a number of other laws were signed for black people who weren't able to come into the country.
In 1945 the law was out here sending decrees & clearly favoring the Europeans.
“In the admission of immigrants, the need to preserve and develop, in the ethnic composition of the population, the more convenient features of their European ancestry shall be considered.”