“For a few years in the 1850s, ethnic conflict among whites rivaled sectional conflict as a major political issue. The immediate origins of this phenomenon lay in the sharp increase of immigration after 1845…. The average quadrupled in the 1830s. But even this paled in comparison with the immigration of the late 1840s…. During the decade 1846 to 1855, more than three million immigrants entered the United States—equivalent to 15 percent of the 1845 population. This was the largest proportional increase in the foreign-born population for any ten-year period in American history…. Equal in significance to the increase in the foreign-born population were changes in its composition.”
James M. McPherson and James K. Hogue, historians, Ordeal By Fire: The Civil War and Reconstruction, 2010.
Which of the following could best be used as evidence to support the argument in the excerpt that “ethnic conflict among whites rivaled sectional conflict as a major political issue” of the period?