The judicial branch , composed of the Supreme Court and lower federal courts, exercises judicial power . Two political parties, the Democratic Party and the Republican Party, have dominated American politics since the American Civil War, although other parties have also existed.
These include increased power of the upper house of the legislature, a wider scope of power held by the Supreme Court, the separation of powers between the legislature and the executive, and the dominance of only two main parties.
The federal government was created by the states, which as colonies were established separately and governed themselves independently of the others.
