Historians have labeled the system of two party competition between the Democratic and Whig parties the "Second American Party System." This system was in place from the winter of 1834, when the Whig party formed in opposition to President Andrew Jackson's supposed executive tyranny, until 1856, when the Whig party was permanently displaced by the Republicans as Democrats' primary opponent. Unlike other systems of two-party rivalry in the nineteenth century, Whigs and Democrats competed with each other in every state of the nation except South Carolina. Although each party was stronger in some states than in others, nationally they were closely balanced. Between 1836 and 1852 Democrats won the presidency in 1836, 1844, and 1852, while Whigs prevailed in 1840 and 1848. Cumulatively during those years, moreover, each party elected almost identical numbers of congressmen. As a result of this close competition, starting in the late 1830s they brought unprecedented numbers of voters to the polls in gubernatorial, congressional, and presidential elections. Whereas turnout hovered at a plateau of 56-57 percent of the eligible electorate in the presidential elections of 1828, 1832, and 1836, for example, it exceeded 80 percent in 1840 and 79 percent in 1844. Although Jackson himself was the primary focus of partisan combat so long as he remained president, between 1837 and 1852 the two parties adopted coherent and sharply contrasting stances in platforms, in roll-call votes in Congress and state legislatures, and on the hustings on governmental economic policy, governmental sponsership of social and moral reforms, and territorial expansion. Starting in the mid-1840s, however, each of these parties began to split along sectional lines over slavery extension, and that sectional rupture would ultimately help cause the system's demise in the mid-1850s.