Inspired by the success of the recent Tunisian and Egyptian revolts, another key state in the Middle East is under pressure from youth-led unrest: Yemen. Again the United States must decide whether to support a corrupt autocrat (albeit one that has been helpful in the war on terror) or face the uncertainty of life without. The Saleh regime in Yemen has been in power for three decades, but major protests led by multiple opposition groups have forced recent concessions, including agreement that neither President Ali Abdullah Saleh nor his son will run for re-election in 2013.

Demographically, Yemen is far younger than both Egypt and Tunisia. Its median age is 18 years old, while Egypt’s is 24 and Tunisia’s, 30. Yemen’s youthfulness makes it far more likely to face violent unrest than either of its relatively peaceful predecessors. And according to demographer Richard Cincotta, given its age structure, it also has a far lesser chance of becoming a stable democracy anytime soon. Yemen’s probability of liberal democracy, based on historical demographic analysis, will not reach the 50/50 point until 2045 (for more on Cincotta’s median age methodology, see his post on Tunisia).

Yemen is not only the fastest growing country in the Middle East, it is also the poorest, with unemployment reaching close to 40 percent, 45 percent of the population living on less than $2 a day, and almost no source of income besides oil exports, which have declined 56 percent since 2001. Yemen’s environment is vulnerable too, with analysts concerned that it could become the first modern country to literally run out of ground water.

These factors mean that Yemen’s revolution, if it comes, likely won’t be anything like Egypt or Tunisia’s relatively peaceful (so far) transitions. For more on Yemen’s unique background and some of the factors leading to its troubled present, see “Demographics, Depleted Resources, and Al Qaeda Inflame Tensions in Yemen.”