Mexico has experienced a significant increase of violence during the first half of 2017. June 2017 saw 2,234 murders in Mexico - the highest rate in over 20 years.

Tops was Tijuana, Baja California, with 714 murders Jan-Jun.

Following was Acapulco, Guerrero with 412 murders. The Mexican daily "Milenio" estimated ~1,800 - 2,000 businesses have closed in Acapulco during the last three years due to high levels of extortion and violence. (I personally know of one small businessperson who was threatened - "pay, leave or suffer the consequences".

Posts above address unsafe areas of Mexico. Many areas are as safe (or safer than) areas of the USA, and like anywhere else there are riskier areas and activities.

That being said, there are still areas of Mexico a visitor is welcome and incurs low risk of violent encounters. Many of those affected in the statistics above were involved directly or in the periphery of the narco trade, as well as human trafficking and other cartel / gang related activity, not foreign visitors.

Another source of problems that exists is of communicable and environmentally trandpsmitted disease. Acapulco has suffered some for years, as "infrastructure " needs were sometimes addressed by piping sewerage offshore, inadequate water handling and treatment, etc.

This problem has spread, according to some knowledgeable people, to the coast north of Puerto Vallarta, like Sayulita. Major growth of resorts, housing and businesses have exceeded investment and preparation in water treatment, potable water, etc.

Link to USCDC "Yellow Book" page on Mexico.