This article provides a summary of the collected evidence that supports the thesis that religion was a salient factor in 19th-century voting behavior. It shows that the United States is essentially an immigrant nation, which is populated by peoples with different languages, social values, cultures, religions, and work experiences. This eventually led to a nation that has a relatively high degree of conflicting norms and values, cultural pluralism, and ethnic diversity. Since religion has been a salient factor in American politics since the 1820s, a religious interpretation of voting behavior can help enhance one's understanding of American political culture from the period of Andrew Jackson to Franklin D. Roosevelt.