In the long run, the most significant division of American opinion exacerbated by the war in Mexico was that between the North and South. The doctrine of America’s manifest destiny had not sprung originally from a slave power conspiracy but from policies with nationwide appeal and deep cultural roots. When James Knox Polk came into office, territorial expansion did not constitute a sectional issue but a party one. . . . Polk did not share Calhoun’s disposition to view all matters in terms of their impact on the slavery question. Nevertheless, as his term went by, his administration increasingly appeared narrowly southern in outlook. The president’s imperialist objectives came to prompt a bitter sectional dispute over slavery’s extension, bearing out Calhoun’s foreboding.
-Source: Daniel Walker Howe, What Hath God Wrought: The Transformation of America, 1815-1848, 2007
The pattern described in the excerpt most directly contributed to which of the following long-term developments?
i. the economic differences between regions
ii. the United States’ efforts to develop the West
iii. the regional divisiveness within political parties
iv. the renewed commitment to Manifest Destiny