According to the U.S. State Department:
Millions of U.S. citizens safely visit Mexico each year for study, tourism, and business, including more than 150,000 who cross the border every day. The Mexican government dedicates substantial resources to protect visitors to major tourist destinations, and there is no evidence that organized criminal groups have targeted U.S. visitors or residents based on their nationality. Resort areas and tourist destinations in Mexico generally do not see the levels of drug-related violence and crime that are reported in the border region or in areas along major trafficking routes……..
U.S. citizens are encouraged to lower their personal profiles and to avoid displaying indicators of wealth such as expensive or expensive-looking jewelry, watches, or cameras. U.S. citizens are encouraged to maintain awareness of their surroundings and avoid situations in which they may be isolated or stand out as potential victims.