. How did the election of 1860 make it clear that the Union was in trouble?

The 1860 presidential election made it clear that the Union was in trouble because the election of Republican Abraham Lincoln caused the secession of the southern states of the country.

Explanation:

The 1860 presidential election was held on November 6, 1860. The election was won by Republican candidate Abraham Lincoln. The Civil War broke out a few months after the election.

The dominant theme of the 1860 election was the struggle between supporters and opponents of slavery. Particularly controversial was the Supreme Court's 1857 decision in Dred Scott v. Sandford, which had legalized slavery in all U.S. territories.

The Republican Party nominated Abraham Lincoln, a former Illinois congressman, as his presidential candidate. Republicans opposed the extension of slavery to territories but did not call for it to be banned in the old slave states.  

The Democratic Party split in two after Illinois Senator Stephen A. Douglas was elected party president in Baltimore in June. Southern Democrats nominated John C. Breckinridge, from Kentucky, as their presidential candidate.

The fourth candidate was John Bell, a former Tennessee senator from the Constitutional Union Party who tried to prevent the Union from disintegrating by avoiding talk of slavery.  

This division between the Democratic Party caused it to lose its force, paving the way for Lincoln's victory. After the election, seven Southern states seceded from the Union and formed the Confederation. Shortly after Lincoln's inauguration, a civil war broke out between the Union and the Confederation.

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