While President James K. Polk had campaigned primarily on foreign policy and expansionist ideology, his experience as speaker of the House had prepared him to deal with the most troublesome domestic issues.

Chief among those issues was the impact that high tariffs had on the Southern economy. Polk had avoided conversation about the Tariff of 1842 during his presidential campaign because he needed votes from the New England and Mid-Atlantic regions, but he understood that a high tariff that protected manufacturing interests had a directly inverse impact on exports from the South to the textile industries in Great Britain.

Polk remembered how the economic panic of the Van Buren administration had destroyed the former president’s legacy. Understanding that finding the ideal balance between protecting Northern interests and encouraging Southern development was crucial, the president charged his secretary of the treasury to draft a law that would address those concerns.

Once a tariff-reduction bill had been drafted, the president needed a champion in the House of Representatives to handle the legislative process. North Carolina Congressman James Iver McKay, who had become the leading North Carolina voice since entering the House during the Jackson administration, was tapped. He guided it through the House Ways and Means Committee, and after intense debate, the House approved the legislation along party lines, with Democrats carrying the vote for the president.

The story was different in the Senate, and the vice president was forced to cast the deciding vote even though his Pennsylvania constituents disapproved of his actions. The passage of the reduced tariff increased international trade, and the late 1840s witnessed a boom period, adding to Polk’s success.

But Polk was not finished with economic issues.

Remember the debate about the Bank of the United States that occurred during the Jackson administration? President John Tyler vetoed an earlier attempt to resurrect the Bank, and Polk was equally opposed. But Polk also did not approve of the current practice in which federal funds were deposited in state banks and then used for regular banking practices, contributing to inflationary trends. Instead, Polk proposed an independent treasury that would control monetary policy. Ultimately approved by both houses of Congress, Polk’s innovation would remain in control until 1913, when the Federal Reserve Act would be enacted.

Polk was making headway with both foreign and domestic policies when the elephant in the room roared once again — the issue of slavery.

As the United States waged war with Mexico over the issue of Texas’s southern boundary and U.S. sovereignty in the region, members of Congress speculated about the possible expanded territories resulting from the conflict. Those who accepted the idea of Manifest Destiny believed that the nation had been chosen to demonstrate to the world that a republic could not only survive but thrive. But others shuddered at the idea of a major territorial gain. How many new states might be added? And would those new states upset the balance of power in Congress?

In an attempt to reduce the possible threat, Congressman David Wilmot attached an amendment to a military appropriations bill that required “neither slavery nor involuntary servitude shall ever exist in any part of” the territory acquired from Mexico. While the amendment passed in the House, it never emerged from committee in the Senate, but the debate identified an increasing tear in the nation’s fabric.

Northern Democrats and Whigs joined together to support the Wilmot Proviso, while Southern Democrats and Whigs fought it. Suddenly, the fight was not between political parties and philosophies but instead was based completely on geographic region. Sectionalism and the issue of slavery — a consideration since the Declaration of Independence, the creation and ratification of the Constitution, and earlier expansion à la the Missouri Compromise — now dominated the debate.

Polk, the Democratic president who could not hold his party together, was weakened by the infighting and attempted to solve the problem by promoting the extension of the Missouri Compromise line. Not satisfied with Polk’s position, Senator John C. Calhoun once again raised his voice and introduced legislation that would allow slave owners to take their “human chattel” to any United States territory without fear of national intervention.

Battle lines that would be expanded in the 1850s had been established, and the issue of slavery would once again dominate the national agenda.