<P> In 1854, the Kansas--Nebraska Act reversed long - standing compromises by providing that each new state of the Union would decide its posture on slavery . The newly formed Republican Party stood against the expansion of slavery and won control of most northern states (with enough electoral votes to win the presidency in 1860). The invasion of Bloody Kansas by pro - and anti-slavery factions intent on voting slavery up or down, with resulting bloodshed, angered both North and South . The Supreme Court tried to resolve the issue of slavery in the territories with a pro-slavery ruling in Dred Scott v. Sandford that angered the North . </P> <P> After the 1860 election of Republican Abraham Lincoln, seven Southern states declared their secession from the United States between late 1860 and 1861, establishing a rebel government, the Confederate States of America on February 9, 1861 . The Civil War began when Confederate General Pierre Beauregard opened fire upon Union troops at Fort Sumter in South Carolina . Four more states seceded as Lincoln called for troops to fight an insurrection . </P> <P> The next four years were the darkest in American history as the nation tore at itself using the latest military technology and highly motivated soldiers . The urban, industrialized Northern states (the Union) eventually defeated the mainly rural, agricultural Southern states (the Confederacy), but between 600,000 and 700,000 American soldiers (on both sides combined) were killed, and much of the infrastructure of the South was devastated . About 8% of all white males aged 13 to 43 died in the war, including 6% in the North and an extraordinary 18% in the South . In the end, slavery was abolished, and the Union was restored, richer and more powerful than ever, while the South was embittered and impoverished . </P> <P> By the 1840s, the Industrial Revolution was transforming the Northeast, with a dense network of railroads, canals, textile mills, small industrial cities, and growing commercial centers, with hubs in Boston, New York City, and Philadelphia . Although manufacturing interests, especially in Pennsylvania, sought a high tariff, the actual tariff in effect was low, and was reduced several times, with the 1857 tariff the lowest in decades . The Midwest region, based on farming and increasingly on animal production, was growing rapidly, using the railroads and river systems to ship food to slave plantations in the south, industrial cities in the East, and industrial cities in Britain and Europe . </P>

What category of land use accounts for an enormous one fifth of urban land in the united states