The Civil War split America in two and then brought it back together again. But the new America was not the same as there were many contentious
interests after the war, expansion, and immigration. America was now much
more pluralistic and would face new problems into the future, including
many dealing with foreign policy. The system as it grew also excluded more
people, and new forces would come to influence American politics such as
populism and immigrants, and America would become a much more pluralistic
nation. It would however be federal, as the Civil War established America
as a sovereign nation and not a confederacy of states, and America would
enter the 20th century as primarily a two party liberal democracy.
The American political system underwent major changes as it started as
nothing, then became a land the be exploited by Europe, then because
colonies of England, then adopted some English models but applied new ideas
of liberal republicanism to a system that ended up becoming...

Through all this change and evolution, however, the original notions of freedom existed and did not go away, but they perhaps even were
extended further as many people wanted to go America because of the notions
of freedom in its political system that it offered. The political system
thus had a lot to offer, and had evolved from nothing into one of the most
free and egalitarian in the world. But there bumps on the road as
witnessed by the divisions of the Civil War as it was not always clear
which way the democracy would go, or if the Union would remain as one, but
in the end America persisted and would go into the 20th century as a highly
complex political nation whose forces over the years continued to change
and alter not only the political landscape, but the political system as
well. The political system, however, consisted of the same components of
the earliest days of the Constitutional Convention, cemented by the outcome
of the Civil War.