Manifest destiny was the idea that the United States would stretch from sea to sea as a beacon of liberty. Texas had lots of American immigrants at the time and had a lot of slave plantations that could of extended the south. Texas also had recently broken free from Mexico, and was made by American settlers who made their government based on the US. So, because of all this, America decided to annex Texas and incorporate it into the Union.
The Compromise of 1877, also known as the "Corrupt Bargain" or the "Great Betrayal" marked the end of Reconstruction in the South and a return to "Home Rule". The Compromise of 1877 was reached to settle the disputed 1876 U.S. Presidential election.
The paradox of President Jefferson tried to put an end to slavery. It was the best lens for the national tensions which then resulted in the bloodiest war to ever occur in American history.