The executive branch includes the president (who is elected by the whole country) and their staff, as well as the various departments and agencies such as the FBI, USDA, NASA, etc, which are staffed by unelected government employees.

The legislative branch (Congress) consists of representatives elected by the people of each state.

The judicidal branch is the courts, and the Supreme Court is the highest court. Its 9 justices are nominated by the president and confirmed by a vote in Congress, and serve for life.