The U.S. State Department issued a travel warning on Jan. 10 to U.S. citizens for five Mexican states affected by high levels of violent crime.
Colima, Guerrero, Sinaloa, Michoakan and Tamaulipas were all placed at level 4 on the State Department's travel advisory scale, comparable to conflict zones like Afghanistan, Iraq and Syria, the BBC reported.
A category 4 rating amounts to a "do not travel" advisory, according to the Los Angeles Times.
With regard to the situation in Tamaulipas, the State Department noted that gun battles are a frequent occurrence.
"Local law enforcement has limited capability to respond to violence in many parts of the state," it added, according to the BBC.
Guerrero, which includes the once-popular resort town of Acapulco, was declared off-limits for U.S. government employees.
The State Department pointed out that "in Guerrero state, armed groups operate independently of the government in many areas."
"Members of these groups frequently maintain roadblocks and may use violence towards travelers," the advice added.
The town of Tecoman in Colima state was the deadliest municipality in the country in 2016, according to government statistics reported by HuffPost.
Overall, the State Department gave Mexico a category 2 classification, meaning U.S citizens should "exercise increased caution."
"Violent crime, such as homicide, kidnapping, carjacking, and robbery, is widespread," added the advisory.
The State Department advised travelers to use toll roads if possible and avoid driving at night. Visitors should not display signs of wealth, such as wearing an expensive watch, and remain highly vigilant when visiting banks or ATMs.
Finally, the advisory suggested having a contingency plan for an emergency situation.
In the first 11 months of 2017, Mexico registered 22,409 killings. This figure is higher than during any year since the government began publishing crime statistics in 1997.
In Baja California Sur, where the tourist destination of Los Cabos is located, there were 62 homicides per 100,000 residents between January and November 2017. This is two-and-a-half times the homicide rate in Chicago.
However, U.S. authorities decided to maintain a category 2 rating for Los Cabos. They did the same for Cancun, another tourist destination.
Mexican authorities had appealed to Washington to keep the two tourist destinations off the category 4 list. Tourism is worth around $20 billion annually to the Mexican economy, equating to roughly 7 percent of the country's economic output.
"I'm guessing they are breathing a sigh of relief," security expert Alejandro Hope told the Los Angeles Times.