Africa.

• Position: 2014 America's Challenges - Statistical data

Kenya

A deadly attack on a shopping mall in Nairobi by Al Shabab--the Islamic militant group based in neighboring Somalia--highlighted the threat that Islamic terrorism still poses in East Africa. It was the worst act of terrorism in Kenya since Al Qaeda's 1998 bombing of the U.S. embassy in Nairobi.

Somalia

The U.S. has funded counterterrorism efforts in Somalia, which has been without a functioning government since 1991. The lawless nation has been a haven for radical Islamist groups like AI Shabab and a breeding ground for pirates, who threaten international shipping in the Gulf of Aden.

By the Numbers 3 Average number of years a Somali child attends school (U.S.: 17 years)

SOURCE: THE WORLD FACTBOOK 2013 (C.I.A.)

Zimbabwe

Robert Mugabe (above), the country's only ruler since its independence in 1980, claimed victory in a disputed election in July. His continued rule leaves little hope that anything will change in Zimbabwe, where the once-thriving economy has been in collapse for the past 13 years.

By the Numbers

95%

Zimbabwe's unemployment rate

SOURCE: THE WORLD FACTBOOK 2013 (C.I.A.)

AIDS

An immune system disease that's deadly if not treated, AIDS has hit Africa particularly hard: Of the 34 million people infected worldwide, almost 70 percent live in sub-Saharan Africa. More than 17 million Africans-including more than 3 million children-have died since the epidemic began about 30 years ago.

Political Systems Around the World

Communist one-party state: Land and businesses are government-owned, and individual and political freedoms are severely limited. (Example: North Korea) The definition has become muddied, since China and Vietnam are allowing an increasing amount of private enterprise.

Constitutional monarchy: A king or queen is head of state but has limited power. An elected parliament (legislature) chooses the prime minister, who leads the government. (Thailand)

Dominant party: A system in which one political party rules. Other parties may exist but have relatively little power. (Zimbabwe)

Military rule: The leader of a country's armed forces controls the government. (Republic of Congo)

Monarchy: A king, queen, or prince rules the government, usually for life and by hereditary right. (Saudi Arabia)

One-party dictatorship: A single party and its leader hold power. (Eritrea)

Parliamentary democracy: Voters elect the parliament. A prime minister, usually leader of the party with the most seats in parliament, heads the government. (Canada)

Presidential dictatorship: The president has almost complete power. (Syria)

Presidential-legislative democracy: An elected president leads the government, sharing power with a legislature and with the courts. (Brazil)

Presidential-parliamentary democracy: An elected president is chief executive. A prime minister leads the government. (South Korea)

Traditional chiefs: A body of tribal leaders plays a role in governing. (Marshall...