The structure of American government is outlined in the United States Constitution, which provides for a federal government with separation of powers and checks and balances. The Constitution also provides for a representative government that is limited in its powers.
A federal government has powers divided between a strong national government and the fifty state governments. The national government has such delegated powers as declaring war, maintaining the armed forces, and regulating interstate commerce. State governments can exercise powers not given to the United States and not denied to the states by the Constitution. The power to establish local governments, an educational system, and traffic and safety laws are examples of powers reserved to the states.
On both levels of government, the powers are separated into three branches, the legislative branch that makes the law, the executive branch that enforces and carries out the law, and the judicial branch that interprets and applies the law to specific cases.
Although the branches are separate and distinct, each of the branches can exercise a series of restraints on the other branches. For instance, the President can veto an act passed by Congress and the Congress can override a veto by a two-thirds vote.
The Constitution provides for a government that is representative through the election of members of Congress, the lawmaking branch. All branches are limited in powers by restrictions placed on them in various parts of the Constitution. The Supreme Court, through its power of judicial review, can determine when any of the parts of government act contrary to the Constitution.
Our two-party system began in the early days of our country. It began with the controversy over the ratification of the Constitution. The Federalists favored ratification, and the Anti-Federalists opposed it. After the Constitution was ratified, the Anti-Federalists changed their name to Jeffersonian Republicans, and then to Democratic-Republicans, and finally to Democrats.
During this time, the Federalists were led by Alexander Hamilton who believed that the government should help business, while the Anti-Federalists were led by Thomas Jefferson who believed the government would take a less active role in society. Jefferson believed in the "common man."
As it happened, the Federalist party was broken up in 1800, and by 1816 had died, leaving only the Democratic-Republicans for several years. This time was called the Era of Good Feeling. By Andrew Jackson's time, however, opposition had grown to the Democrats, and a new party, the National Republican Party, known as the Whigs, had sprung up.
Therefore, the Whigs and the Democrats were the two major parties until the issue of slavery divided the nation in the 1850s, and both parties were split by that controversy.
During the 1850s, the Republican Party grew up as a third party, and it elected its first president, Abraham Lincoln, in 1860. The Republican Party became the only minor party to become a major party. Since that time, there have been the two major parties, Republicans and Democrats.