This idea like so many of Sanger’s musings was eventually taken up by a sympathetic and powerful politician and resulted in a famous set of laws ... in Nuremberg, 1935.
A lot of it was actually adopted at the state level across the nation. Involuntary sterilization of those deemed inferior was widely practiced. Euthanasia saw limited use as well. Not our finest moment.
http://en.wikipedia.org/wiki/Eugenics_in_the_United_States