However, the party system could not overcome the increasingly sharp sectional divisions. As the North developed into an urban industrial society based on free labor, the South increasingly defended white supremacy and slavery as a “positive good” and expanded its plantation-based agricultural society. Beginning in the 1820s, the two sections had differed over economic issues and Indian policy. Georgia and other southeastern states demanded and won — over the objections of northeastern reformers — the Indian Removal Act of 1830, which resettled native peoples west of the Mississippi River. Concurrently, between 1816 and 1832, northern manufacturers, workers, and farmers won high protective tariffs, which southern planters bitterly opposed. Eventually, party politicians negotiated a compromise, with the North accepting tariff reductions. The sections had clashed again over the expansion of slavery, into Missouri and the Louisiana Purchase in the 1820s and into Texas and the Southwest in the 1840s, and political leaders again devised compromises. However, by the 1850s, slavery — and the social system it symbolized — increasingly divided the nation. Moreover, because the democratic political revolution had engaged the passions of millions of ordinary Americans, the political system had become more volatile and resistant to compromise. Chapters 10 and 12 explain how national expansion led to increasing sectional struggle.