More than 200,000 people have been killed or have disappeared since Mexico’s government declared war on organised crime in December 2006.
The military offensive has led to the destruction of some drug gangs, splits within others and the emergence of new groups.
With widespread corruption and impunity exacerbating Mexico’s problems, there is no end in sight to the violence.
Which are the most powerful cartels today? And who is behind them?
The Sinaloa cartel
Founded in the late 1980s, the Sinaloa cartel headed by Joaquín “El Chapo” Guzmán has long been considered Mexico’s most powerful criminal organisation.
Having outfought several rival groups, the Sinaloa cartel dominates much of north-west Mexico and makes billions of dollars from trafficking illicit narcotics to the United States, Europe and Asia.
The Jalisco New Generation
Sinaloa’s strongest competitor is its former armed wing, the Jalisco New Generation cartel. Formed around 2010, the Jalisco cartel has expanded rapidly and aggressively across Mexico and is now challenging Sinaloa for control of strategic areas, including Tijuana and the port of Manzanillo.
The Jalisco cartel is blamed for a series of attacks on security forces and public officials, including downing an army helicopter with a rocket-propelled grenade in 2015. Mexico’s Attorney General Raul Cervantes recently declared it the nation’s largest criminal organisation.
What happened after El Chapo’s arrest?
Guzmán’s latest arrest created a split within the Sinaloa cartel, fuelling rising violence in the region.
On one side are Guzmán’s sons, Iván Archivaldo and Jesús Alfredo. On the other side, his former associate Dámaso López Núñez, alias “El Licenciado”, and his son Dámaso López Serrano.
Guzmán’s sons were kidnapped at a restaurant in Puerto Vallarta last year but released days later. López Senior was among the suspected culprits. Guzmán’s sons also accused him of leading them into a near-fatal ambush in February.
López Senior was arrested in Mexico City in May. The cartel leadership remains under dispute.
Guzmán’s older brother Aureliano is another influential figure vying for control, while Fausto Isidro Meza Flores, alias “Chapo Isidro”, has emerged as one of the cartel’s powerful local adversaries.
Who are Mexico’s most wanted?
Ismael “El Mayo” Zambada, an elusive veteran who ran the Sinaloa cartel alongside Guzmán, is one of the Mexican government’s primary objectives.
Aged 69, Zambada is nearing retirement but is said to retain strong influence behind the scenes. Mexico offers a 30 million peso (£1.2m) reward for information leading to his capture.
Ruben Oseguera, alias “El Mencho”, the head of the Jalisco New Generation cartel, is another of Mexico’s most wanted kingpins. A former police officer and avocado vendor, he is the subject of a two million peso (£82,000) bounty.
Rafael Caro Quintero, the founder of the now-defunct Guadalajara cartel, is the DEA’s most wanted fugitive. Convicted of the abduction, torture and murder of DEA agent Enrique Camarena in 1985, he served 28 years of a 40-year sentence in Mexico before being released after a court ruled he should have been tried in a state rather than a federal court.
The US state department offers rewards of up to $5m (£3.8m) for information on Caro Quintero, Zambada or Oseguera.
What happened to Mexico’s other major players?
In eastern Mexico, the Gulf cartel and their fearsome former allies Los Zetas have been weakened by killings and arrests of top leaders, leading to splits within both groups.
In western Michoacán state, the pseudo-religious Knights Templar and La Familia cartels have been largely vanquished by vigilante groups, although the region remains contested by their remnants and several newer gangs.
To the north, the once mighty Juárez, Tijuana and Beltrán-Leyva cartels have all been weakened by Sinaloa cartel offensives.
How has the criminal landscape changed?
Mexico’s criminal landscape has grown more fragmented since then-President Felipe Calderón sent the army to combat the cartels in December 2006.
The government succeeded in capturing or killing the leaders of the biggest cartels, but this led to many smaller and often more violent gangs springing up in their place.
Without the capacity for transnational drug trafficking, these gangs deal in kidnapping, extortion, human trafficking, illegal logging and mining, and stealing oil from government pipelines.
Are things better or worse than they were?
The level of violence dropped after the election of President Enrique Peña Nieto in 2012, but it has shot up dramatically in the last two years, with 2017 on course to be the worst year on record.
Activists and journalists are routinely murdered, while corruption and impunity remain rampant.
The legalisation of marijuana in parts of the US has driven Mexico’s cartels to push harder drugs like methamphetamine, heroin, and fentanyl, a powerful synthetic opioid. This has fuelled an epidemic north of the border, with provisional figures from the US Centers for Disease Control and Prevention suggesting that more than 64,000 Americans died from drug overdoses in 2016, up 21% from the previous year.
How violent are the cartels?
Mexico’s cartels are notorious for their extreme violence. Beheadings and torture have become commonplace over the past decade.
Victims are sometimes hung from bridges or dissolved in barrels of acid. Some cartels post graphic execution videos on social media to intimidate their enemies.
How many people have died?
Mexico registered more than 200,000 murders from January 2007 to December 2016, according to government records. More than 30,000 people are classified as disappeared in that same timeframe.
With 23,953 murders, the homicide rate in 2016 was lower than in the years between 2010 and 2012. But preliminary figures for 2017 suggest the past 12 months could turn out to be the worst yet in the last decade.
The final figures for 2017 are expected to be published in July 2018.