What were the most important things about foreign policy and politics during the Expansion/Pre-Civil War (1829-1859) era?

This is a vast subject, one on which many books could and have been written.  I will only be able to give you the bare details in this space.

The most important political issue during this entire time was the issue of slavery and how far it would expand.  There was also the connected issue of states’ rights.  Practically all of the politics of the time centered around these issues.  Let us look at some of the major events that occurred during this time period that had to do with these issues.  They include:

• The Nullification Crisis of 1832-3.  This had to do with whether states could ignore laws made by the national government if they thought those laws were unconstitutional.  This was the first time a Southern state made serious moves towards seceding from the Union.


• The domestic conflict over the war with Mexico that started in 1846.  While the war itself was a foreign policy issue, there was great conflict over the meaning of that war in the US.  Anti-slavery people felt that the war was being fought to expand slavery.  A term to know here is Wilmot Proviso, which tried to stipulate that slavery would be barred from any land taken from Mexico.


• Compromise of 1850.  This was supposed to solve the problem of slavery in the Mexican Cession.  However, it enflamed tensions between the North and the South, largely because of the Fugitive Slave Act, which was part of the Compromise.


• Kansas-Nebraska Act of 1854, which threw out the Missouri Compromise and opened up the debate over slavery in the territories.


• The violence in “Bleeding Kansas” over the issue of slavery from 1856 to 1858.


• The Dred Scott decision of 1857, which said, among other things, that Congress could not regulate slavery in the territories.

These are the most important events that occurred during this time period with regard to the issue of slavery.  All of these episodes served to drive the North and the South further apart, making the Civil War more likely.

There was not that much going on in foreign policy during this time.  The two most important events were the war with Mexico and the deal with the United Kingdom with regard to the Oregon Territory.  The US and the British had jointly controlled the Oregon Territory since 1818.  They agreed to hold it jointly until they could agree to a boundary.  By the early 1840s, American migration to the Oregon Territory forced the two sides to try to agree on the boundary.  This brought some amount of conflict as some Americans wanted to fight unless Britain agreed to give the US the entire Oregon Territory.  This was eventually settled in 1846 with the two sides agreeing to a border at the 49th parallel.

The other major foreign policy issue was the dispute with Mexico.  This started when Texas, which was mainly populated by Americans, broke away from Mexico in 1836.  Texas asked to join the US, which Mexico strenuously opposed as it still refused to accept that Texas was independent.  This led to tension between Mexico and the US.  These tensions came to a head in 1845 when the US annexed Texas.  This led to war between the two countries in 1846.

These are the main issues in politics and foreign policy during this time.  However, please note that this is a terribly brief summary of what happened during a most eventful time in US history.