In the United States, state governments are set up with the same separation of powers—executive, legislative, and judicial branches—as the national government. The governor of a state is a member of the state executive branch.

The Supremacy Clause of the Constitution states that federal, or national, law is the supreme law of the land. This is a key component of American Federalism as opposed to the Confederation that existed under the Articles of Confederation. The Founding Fathers observed that under the Articles, the federal government had too little power and the states were free to make their own disparate laws absolute within their territories. Federalism and the Supremacy Clause remedies this situation by ensuring that all state laws must be within the realm of federal laws.

All fifty of the American states have their own constitutions; however, they are all also required to follow the national constitution first, which remains the “supreme law of the land” as established in the Supremacy Clause of the U.S. Constitution.

One of the core principles of the American political system is Federalism. In Federalism, power and legitimacy is shared by more than one political entity. In the United States, there is the national government, which retains the majority of control over the political arena, but there are also state and local governments, which have their own areas of power and an established legitimacy.

Democracy describes the principle that the legitimacy and power of a government is derived from the people being governed. There are many ways to organize a government in accordance with democratic principles. Direct democracies are marked by the direct participation of voters in decision making. The Swiss government is perhaps the most prominent government that comes close to being a direct democracy. In Switzerland, it is common for groups of voters to band together and make proposals for laws that are then voted upon by the rest of the electorate, often with little input from elected representatives or bureaucrats. Other forms of democracy, like representative democracy, are distinguished by putting most decision-making responsibilities into the hands of elected or appointed representatives who are accountable to voters. 

In a parliamentary democracy, the leader of the executive branch will always be the same as the leader of the legislature. In a presidential democracy, like the the government of the United States, there are separate elections for the legislature and the executive branch. This creates a situation where the presidency and Congress may be controlled by different political parties. Because of this diffusion of power, it is harder to pass legislation in a presidential democracy, as the executive and the legislature might disagree; however, there are more checks and balances in the presidential system.

In order to alter the Constitution of the United States of America, an amendment must be passed by either a two-thirds vote in both the House of Representatives and the Senate or by a constitutional convention called for by two-thirds of the state legislatures.