The United States of America is a federation of 50 states with 48 on the continent, Hawaii in the Mid-Pacific south - west of San Francisco and Alaska in the North. There is also one district, D.C.-District of Columbia. The capital city, Washington D.C., is situated there. Each state is different from all the others. It has its own state government, laws, education, taxes and customs. The structure of American government is really a mosaic composed of thousands of interlocking units. In addition to the federal government, there are 50 state governments and the government of the District of Columbia, and further down the ladder there are still smaller units that govern counties, cities, towns and villages, to name a few.
The Constitution of the USA establishes a stronger federal government empowered to collect taxes, conduct diplomacy, maintain armed forces, and regulate foreign trade and commerce among the states, but most importantly, it establishes the principle of a balance of power. It means that the power in the USA is divided into three branches - legislative, executive and judicial, each one having powers (checks and balances) over the other.