Following up on the Mara Salvatrucha story,
¡Gringo Unleashed! has translated an article from Hola Hoy, and an editorial from Manuel Gutierrez Fierro in La Voz.

Last May The Econonmist wrote on the gang's origins:

The gangs' origins lie in the wars that engulfed Central America in the 1970s and 1980s. To escape these, many Central Americans migrated to the United States, and particularly to Los Angeles. Their children imitated that city's gang culture. In 1992, as the wars were dying down, the United States decided to start deporting jailed gang members when their sentences were over.

The notorious Salvatrucha
Back in countries that were almost foreign to them, with no jobs, the deportees set up their own gangs. According to government estimates, 36,000 people are said to belong to gangs in Honduras, 14,000 in Guatemala, 10,500 in El Salvador, 1,100 in Nicaragua and 2,600 in Costa Rica. The true figure is almost certainly much higher. The most notorious of hundreds of gangs, or maras, is the Mara Salvatrucha, named for its Salvadorean founders who claimed to be as wise as a trout. Its initials appear in graffiti across the region.

A more recent article last month states that, while the number of rural counties and small cities reporting gang activity dropped considerably between 1996 and 2002 and youth gang membership numbers appear to have leveled off, the MS-13, with its wide network and alleged connections to al-Qaeda is a major player:

Violent gangs are increasingly linking up and going international, helped by the internet, immigration and America's deportation of criminals. One especially violent gang under close FBI scrutiny is Mara Salvatrucha (MS), a network of street thugs and former paramilitary guerrillas whose exact genesis is disputed, but which got its first toehold among the children of Salvadorean refugees in Los Angeles. MS now has a stronghold in northern Virginia, as well as in Central America.

As this week's raids have shown, the MS-13 had spread to other parts of the country, including here in NJ.

Prior posts on this subject here and here