In 5 paragraphs, how was the American Civil War the "seminal event" in American history?

I would talk about the following things if I had to write
an essayon this issue:

1. It led to the issue of
   race as a major political issue in the United States.  After the war, the issue of black
   rights becomes a big one and continues to be with us
   today.


2. It led to the creation of the party system that we
   now have.  The coming of the Civil War made the Republican Party viable and the war
   itself gave the party long-term credibility.


3. It led to
   the current situation where the South is politically very different from the rest of the
   nation.  This is going away a bit now, but the South is solidly conservative, and this
   conservatism is based to some degree on the legacy of the Civil War and the racial
   issues that followed.


4. It clearly established the idea
   that the federal government is more powerful than the state governments.  It made clear
   that the states could not override federal laws.  Therefore, in a way, you can say that
   it made the US truly united for the first time in its
   history.