(CNN) Beheadings, mass executions, public hangings and torture -- it's all part of the massive drug war next door.
Mexico's drug wars have claimed more than 80,000 lives between 2006 and 2015, according to analyst estimates in the 2015 Congressional Research Service report.
Fierce rivalries between Mexico's drug cartels have wreaked havoc on the lives of civilians who have nothing to do with the drug trade. Bystanders, people who refused to join cartels, migrants, journalists and government officials have been killed.
So what does it have to do with the United States?
Mexican drug cartels take in between $19 billion and $29 billion annually from US drug sales.
Here are some of Mexico's biggest drug cartels:
The largest illegal drug franchise in Mexico supplies much of the marijuana, cocaine and heroin peddled on the streets of the United States. With roots in western Mexico, the Sinaloa Federation established control of routes through the border states of Chihuahua and Baja California, according to the Congressional Research Service report.
It controls roughly 40% to 60% of the country's drug trade, with earnings at around $3 billion. Although it functions through loose links to smaller organizations, Sinaloa is considered one of the most cohesive.
Sinaloa was formerly led by the world's most notorious drug lord, Joaquin "El Chapo" Guzman. He rose from the streets to run the drug empire by using assassins and hit squads to maintain control.
He first escaped from prison in 2001 after serving eight years of his 20-year sentence. He went on the run for more than a decade.
In 2014, Guzman was arrested again, but he escaped a year later through a hole in the shower of his cell block. After months on the run, he was caught in January and is currently fighting extradition to the United States, where he's expected to face charges of conspiring to import hundreds of thousands of pounds of cocaine into the country between 1999 and 2014.
His son Jesus Alfredo Guzman Salazar was one of six people kidnapped from a restaurant in August in the resort town of Puerto Vallarta, Mexico official said.
Sinaloa has been fighting to maintain dominance in the region amid challenges from a rival cartel, Jalisco New Generation.
This cartel was believed to have made its first appearance in 2011 with a public display of 35 corpses of alleged Los Zetas members. The Mexican government has warned it's one of the most dangerous cartels in the country, especially after it shot down a military helicopter in May 2015. Rubén Oseguera Cervantes, known as "El Mencho," is believed to be the group's leader.
Made up of former elite members of the Mexican military, members of the group initially worked as hit men for the Gulf Cartel before becoming independent. Rather than relying on drug smuggling, they made their mark with an unprecedented level of savagery. They are suspected of targeting migrants who can't pay extortion fees.
Killings were posted on the Internet. Leaving bodies and body parts in public places was a hallmark of Los Zetas' work, as was torture. The group's former leader, Miguel Angel Treviño Morales, aka "El 40" or "Z-40," had a reputation for punishing his foes with "guisos," Spanish for "stew" and the term used for burning someone alive. He was arrested in 2013.
Two years later, his brother -- believed to have taken over the group leadership -- was arrested.
This group had been one of Sinaloa's main competitors in the 2000s, with an extensive transnational network into Central and South America. The group started way back in the 1920s.
It split with its enforcers, Los Zetas, by 2010. The bitter fallout between the two groups has been called the "most violent in the history of organized crime in Mexico," according to the 2015 Congressional Research Service report. The cartel fragmented into smaller groups, and analysts said that the structure of the group has been weakened by government action and its fierce rivalry.
This group was founded by the four Beltran Leyva brothers -- Arturo, Carlos, Alfredo and Hector. They first started out having friendly relations with Sinaloa. But after one of the brothers was believed to be betrayed, they splintered off and became major foes of Sinaloa. The cartel was responsible for transporting weapons and ammunition to Mexico from the United States, and trafficking in cocaine, marijuana, heroin and methamphetamine, according to the US State Department. The group is believed to have declined in recent years after the 2014 arrest of its leader, Hector Beltran Leyva, nicknamed "The Engineer" and "The H."
Formerly aligned with the Sinaloa cartel, this group splintered off, triggering a bitter rivalry in 2008. The fight for control of Ciudad Juarez inflicted heavy violence. In 2014, police captured alleged Juarez Cartel boss Vicente Carrillo Fuentes, known as "El Viceroy."
Based in Tijuana, the group primarily controlled the flow of drugs between Mexico to Southern California. Most of the Arellano Felix brothers have been apprehended or killed.