Final answer:
The anti-immigrant movement that began in the 1840s in America was known as the Know-Nothing Party. They aimed to curb Catholic immigration, feared for its impact on republican values, and were later involved in legislating immigration restrictions.
Step-by-step explanation:
The anti-immigrant movement in America that began in the 1840s was called the Know-Nothing Party, also known as the American Party. It emerged primarily as a reaction to the influx of Irish and German Catholic immigrants, whom the nativist Americans saw as a threat to the nation's republican values. The Know-Nothings were characterized by their secretiveness, as suggested by their nickname which stemmed from their typical response, "I know nothing," when questioned about the party. By the mid-1850s, the party gained considerable political influence with over one million members, becoming a significant force, particularly in the North.
The Know-Nothing Party was also associated with the broader xenophobic and discriminatory sentiments prevalent in the late 19th century, leading to anti-immigration legislation. This culminated in laws like the Emergency Quota Act of 1921, the Immigration Act of 1924, and the National Origins Act, which sought to restrict the immigration of specific national and ethnic groups. These legislative acts were influenced by earlier nativist groups and campaigns such as the American Protective Association's advocacy for immigration curbs.