The United States won the The Mexican–American War in the 1840s, and with it vast new stretches of western land. But in the 1850s, the question of what to do with this land – and whether to allow slavery in the new territories or not – became a redning issue for politicians of all stripes.While the Whig Party collapsed over the issue, Democrats split into Northern and Southern factions, and a new Republican Party tried to bind the Union with an appeal to old Jeffersonian values. But in the houses of Congress and across the nation, negotiations fail, compromise is abandoned; and the issue of slavery will overshadow all else, leading to Civil War.Support this show by supporting our sponsors! Quip - Order and get your first refill pack free at GetQuip.com/TellersThe Great Courses - Sign up and learn at TheGreatCoursesPlus.com/Tellers On Deck - Learn more at OnDeck.com/Tellers