Final answer:
Eugenics was popular in the early to mid-20th century, especially in the 1920s and 1930s, and was organized both in the United States and Nazi Germany. The movement led to forced sterilizations and research promoting genetic superiority, culminating in the atrocities committed by the Nazis.
Step-by-step explanation:
Eugenics was most popular during the early to mid-20th century, particularly in the 1920s and 1930s. This pseudoscientific movement was organized in several countries, including the United States and Germany. In the U.S., the movement was widespread, with government-funded forced sterilization programs in 32 states targeting tens of thousands of women, primarily people of color.
Influential organizations such as the Carnegie and Rockefeller foundations supported research that claimed to show the hereditary inferiority of certain groups. The most infamous manifestation of eugenics was in Nazi Germany's program, which involved forced sterilizations and the systematic killing of those deemed unfit, in an attempt to create a genetically superior Aryan race. The Second International Eugenics Conference, exemplifying the movement's international aspirations, took place in New York City in 1921.