Scholastic
Scholastic: Nativism
Scholastic gives both a general definition of nativism and also in reference to the 19th century United States. It gives examples and explanations of why nativism developed in the 19th century United States.
Northern Illinois University
National Campaign Materials 1840 1840: Political Culture: Nativism
This site has an article about pre-Civil War nativism as it was fueled by anti-immigrant groups and anti-Catholicism.
Tom Richey
Tom richey.net: The Crisis of the Union (1850 1860) [Ppt]
Presents key ideas for examining the events and issues that led to the American Civil War.