"Americans encouraged relatively free and open immigration during the 18th and early 19th centuries, and rarely questioned that policy until the late 1800s. After certain states passed immigration laws following the Civil War, the Supreme Court in 1875 declared regulation of immigration a federal responsibility. Thus, as the number of immigrants rose in the 1880s and economic conditions in some areas worsened, Congress began to pass immigration legislation. [...] The federal government assumed direct control of inspecting, admitting, rejecting, and processing all immigrants seeking admission to the United States with the Immigration Act of 1891. The 1891 Act also expanded the list of excludable classes, barring the immigration of polygamists, persons convicted of crimes of moral turpitude, and those suffering loathsome or contagious diseases. [...] At the beginning of the 20th century, federal attention next turned to standardizing naturalization procedures nationwide. [...] To normalize naturalization procedures, the Basic Naturalization Act of 1906 required standard naturalization forms and encouraged state and local courts to give up their naturalization jurisdiction to federal courts. To prevent fraud, the new federal Naturalization Service collected copies of every naturalization record issued by every naturalization court across the country. Bureau officials also checked immigration records to verify each applicant's legal admission into the United States."
U.S. Citizenship and Immigration Services: http://www.uscis.gov/