USA is a republican federal state compounded with 50 individual states
The form of government was established in Philadelphia in May of 1787, with George Washington presiding. The resulting master plan, or Constitution, set up a system in which some powers were given to the national, or federal, government, while others were reserved for the states. The Constitution divided the national government into three parts, or branches: the legislative (the Congress, which consists of a House of Representatives and a Senate), the executive (headed by the president), and the judicial (the federal courts). Called "separation of powers".
Bill of rights
The Bill of Rights guarantees Americans freedom of speech, of religion, and of the press. They have the right to assemble in public places, to protest government actions, and to demand change. There is a right to own firearms. Because of the Bill of Rights, neither police officers nor soldiers can stop and search a person without good reason. They can’t search a person's home without permission from a court to do so. The Bill of Rights guarantees a speedy trial to anyone accused of a crime.
The legislative branch -- the Congress -- is made up of elected representatives from each of the 50 states. It is the only branch of U.S. government that can make federal laws, levy federal taxes, declare war, and put foreign treaties into effect.
The judicial branch is headed by the U.S. Supreme Court, which is the only court specifically created by the Constitution. In addition, Congress has established 13 federal courts of appeals and, below them, about 95 federal district courts. The Supreme Court meets in Washington, D.C., and the other federal courts are located in cities throughout the United States. Federal judges are appointed for life or until they retire voluntarily; they can be removed from office only via a laborious process of impeachment and trial in the Congress.
The court of last resort
Although the three branches are said to be equal, often the Supreme Court has the last word on an issue. The courts can rule a law unconstitutional, which makes it void. Most such rulings are appealed to the Supreme Court, which is thus the final arbiter of what the Constitution means.
Political parties and elections
Americans regularly exercise their democratic rights by voting in elections and by participating in political parties and election campaigns. Today, there are two major political parties in the United States, the Democratic and the Republican. The Democratic Party evolved from the party of Thomas Jefferson, formed before 1800. The Republican Party was established in the 1850s by Abraham Lincoln and others who opposed the expansion of slavery into new states then being admitted to the Union.