Immigration into the United States was relatively free of restrictions during the nation’s first century. Immigrants were desperately needed to settle and build the young country. Furthermore, the U.S. Constitution was unclear about whether the responsibility for regulating immigration belonged to the states or the federal government. The Alien and Sedition Acts—which made it more difficult for immigrants to become citizens and permitted the deportation of anyone who criticized the government, president, or Congress—were passed by Congress in 1798 but expired two years later. In 1819 Congress passed its first significant law concerning immigration. The law required all immigrants to provide their name, age, and occupation when entering the United States, and in 1820 the United States began keeping records of immigrants entering America.

Following the Civil War (1861–1865), labor unions began agitating for laws restricting immigration...