Nineteenth-Century Americans associated with the nativist American Party (a.k.a., “Know Nothings”) proposed extended probationary periods before immigrants could apply for U.S. citizenship. They also forwarded other policies aimed to press the assimilation of (mainly) Catholic immigrants, or at least to mold immigrant behavior to conform with the predominant scruples of American Protestants. (Some latitude was allowed German Lutherans, particularly with respect to temperance.) While nativist, however, the Know Nothing movement did not broadly advocate restrictions on immigration. I wondered in a prior post whether the Americanism of the American Party, namely, a commitment to the natural-rights position of humanity’s common ownership of the earth (consistent with the natural rights philosophy articulated in the Declaration of Independence at the nation’s founding), channeled their energies toward assimilation and away from restrictions.