Britannica Student Encyclopedia - 2010

finally guaranteed many rights to African

Americans.

After the ColdWar

Relations between the United States and

the Soviet Union improved in the

1980s. In 1991 the Soviet Union broke

up, ending the ColdWar.

In the early 21st century the United

States worried more about threats from

terrorists than from other countries. In

2001 members of a terrorist group called

al-Qaeda hijacked (seized) four airplanes

and crashed three into buildings. The

attacks killed nearly 3,000 people.

After the attacks President GeorgeW.

Bush announced a “war on terror.” The

United States attacked Afghanistan in

2001 and Iraq in 2003. Bush accused

the leaders of both countries of supporting

terrorism.

In 2008 the United States elected its

first African American president. The

new president, Barack Obama, faced

many difficulties. They included the

ongoing wars in Iraq and Afghanistan

and a troubled economy at home.

..More to explore

American CivilWar • American

Revolution • Americas, Exploration and

Settlement of the • Confederate States of

America • Great Depression • Korean

War • Louisiana Purchase • Native

Americans • Reconstruction • Spanish-

AmericanWar • United States

Constitution • VietnamWar

•Washington, D.C.

BRITANNICA STUDENT ENCYCLOPEDIA United States 31

 

United States

Constitution

The United States Constitution is the

most basic law of the United States. All

other laws—including local, state, and

U.S. laws—must agree with the U.S.

Constitution.

History

No other country has a written

constitution that is older than the U.S.

Constitution.However, the Constitution

was a replacement for an even older set of

rules called the Articles of Confederation.

The articles were written when the

United States first became a country.

But there were problems with the

articles. In 1787 people met in Philadelphia,

Pennsylvania, to change them.

They soon wrote a completely new

document—the Constitution. Alexander

Hamilton and others then wrote essays

known as the Federalist papers to

explain the new Constitution.

During this time, the United States had

13 states. The Constitution went into

effect on March 4, 1789, after nine

states had approved it. All 13 states

approved it by 1790.

Federal System

The Constitution gave the United States

a federal system. In a federal system different

levels of government share power.

In the United States the national, or

federal, government shares power with

the governments of the states. Even so,

the national government gained more

power under the new Constitution than

it had had under the Articles of Confederation.

Separation of Powers

The writers of the Constitution also

wanted U.S. government leaders to share

power with each other. So they separated

the government into three equal

branches—legislative, executive, and

judicial.

Checks and Balances

Each branch has some power over the

others. This is called a system of checks

and balances. For example, the leader of

the executive branch (the president) gets

to appoint, or choose, many government

leaders. But part of the legislative branch

(the Senate) has the power to reject the

president’s choices.

Amendments

The Constitution can be changed.

Changes are called amendments.

Amending the Constitution is hard to

do. Two thirds of each house of Con-

A painting shows members of the Constitutional

Convention signing the United States

Constitution in 1787.

32 United States Constitution BRITANNICA STUDENT ENCYCLOPEDIA

 

gress and three fourths of the states must

approve every amendment.

The first 10 amendments went into

effect in 1791, only two years after the

Constitution became official. Those

amendments are called the Bill of

Rights. Only 17 other amendments have

been added to the Constitution since

1791.

#More to explore

Amendment • Articles of Confederation

• Bill of Rights • Federalist Papers

United States

Government

The United States government gets its

powers from the United States Constitution.

The Constitution organized the

government into three equal branches—

legislative, executive, and judicial.

Legislative Branch

The legislative branch of a government

holds the power to make laws. In the

United States, Congress is the legislative

branch. Congress also has the power to

declare war. A few legislative agencies,

like the Library of Congress, help Congress

in its work.

Members of Congress

Congress consists of two groups called

houses. One house is the Senate. There

are 100 senators, two from each state.

The other house is the House of Representatives,

or House. There are 435 representatives

in the House. The number

of representatives from each state is

based on the state’s population. States

with large populations have more representatives

than states with small populations.

Senators serve six-year terms. All voters

in a state elect both senators from that

state. States that have more than one

representative, however, are divided into

districts. People vote only for the representative

from the district in which they

live. Representatives serve two-year

terms.

Both houses of Congress have leaders.

The House leader is called the speaker

of the House. The political party that