In the 1770s when the American colonies were fighting against Britain, they formed a 'Confederation'. This is a weak form of union. Representatives of each State sometimes met at the Federal Congress, but at these meetings they were strictly representing the interests of State, not of the people. In fact, the Federal Congress could not even enforce its laws on individual citizens; it had to ask each state to do that.

 After the War of Independence, the Americans wrote a Constitution for the Union of States in 1787. In the process they invented a completely new kind of union, called a "Federation", a system which is still in use today. According to the Constitution, the Federal Government controls defence, foreign policy, the currency and trade between States. The States control education, the police and internal regulations. 

For Americans democracy means more than majority rule. It also means minority rights. A Bill of Rights guarantees freedom of speech and organization. To prevent any one politician or party from becoming too powerful, the powers of the Federal Government are divided.

The Congress writes the laws. It is made up of the House of Representatives and the Senate. The Congress meets in the United States Capitol in Washington, D.C. Congress has 535 voting members: 100 senators and 435 representatives. Both senators and representatives are chosen through direct election. The members of the House of Representatives are elected for the two-year term of a Congress. Each senator is elected at-large in their state for a six-year term. Each state, regardless of population or size, has two senators, so currently, there are 100 senators for the 50 states. At the start of each two-year session, the House elects a speaker who serves as the majority party's leader. In the Senate, the vice president is the ex officio president of the Senate. 

The President carries out the laws and policies of the Government. The president is also the chief executive of the federal government and Commander-in-Chief of the  armed forces. The Unites States was the first nation to create the office of President as the head of state in a modern republic.  

The courts enforce the laws and are kept independent so they can do this without political bias. The Supreme Court decides whether the laws themselves are legal, or unconstitutional.  

(adapted from Speak Up, Rachel J. Roberts)