Eugenics had roots that preceded recorded history: the idea of selective breeding. Thus, selective breeding turned wild species into domesticated crops and livestock. By the beginning of the 20th century, every farmer appreciated the value of agricultural selection. A majority of Americans were still living in rural areas during the first several decades of the 20th century, and fairs were major cultural events. Farmers brought their products of selective breeding -- fat pigs, speedy horses, and large pumpkins -- to the fair to be judged. Why not judge "human stock" to select the most eugenically fit family? Hence the Fitter Families Contests were born. In 1905, psychologist Alfred Binet developed a measure of "mental age" to help steer elementary students to academic or vocational tracks. .
Eugenicists effectively lobbied for social legislation to keep racial and ethnic groups separate, to restrict immigration from southern and eastern Europe, and to sterilize people considered "genetically unfit." This became highly publicized and unfortunate. Elements of the American eugenics movement were models for the Nazis, whose adaptation of eugenics culminated in the Holocaust. .
The eugenics movement coincided with one of the busiest times in U.S. immigration. During the first two decades of the 20th century, 600,000-1,250,000 immigrants per year entered the country through Ellis Island (except during World War I). Eugenicists worried that the new immigrants weakened America biologically, and lobbied for federal legislation to selectively restrict immigration from "undesirable" countries. The Immigration Restriction Act of 1924, sponsored by Committee Chairman Albert Johnson, House of Representatives Committee on Immigration and Naturalization, did everything eugenicists had hoped for. The Johnson Act limited immigrants from each country according to their proportion in the U.S. population in 1890.
