Stephen Douglass was a Democrat elected to the U.S. Senate in 1858. Douglas defeated Abraham Lincoln to obtain his Senate seat. He was a supporter of the idea of popular sovereignty, the belief that the settlers in newly admitted territories should determine whether the area would be slave or free. Douglass received the Democratic nomination for president in 1860. Douglass support of popular sovereignty led to the splintering of the Democratic Party into Northern and Southern factions. Northerners opposed secession while Southerners supported it. The splintering of the party led to their defeat and the election of the Republican Abraham Lincoln in 1860.
Because the U.S declared that the people of Kansas and Nebraska can vote on to be a slave or free state, in this case northerners rushed there to make it a free state, this whole thing also caused bleeding Kansas
A because mexico renter ed the 20th centriy
To celebrate Thanksgiving? Research on it maybe, im sorry i couldnt help :(