Americans urged to be cautious when traveling to Mexico

(CNN) -- Americans should avoid all but essential travel to all or parts of 14 Mexican states, the U.S. State Department warns as violence has spread.

Shootouts, kidnappings and carjackings have climbed, as have cartels, also known as transnational criminal organizations (TCO), the State Department said this week in a broadened travel warning.

While millions of U.S. citizens safely visit Mexico every year, the country's ongoing violence and security concerns pose risks for U.S. citizens, and travelers should take precautions, the State Department advises.

"The TCOs themselves are engaged in a violent struggle to control drug trafficking routes and other criminal activity. As a result, crime and violence are serious problems throughout the country and can occur anywhere. U.S. citizens have fallen victim to TCO activity, including homicide, gun battles, kidnapping, carjacking and highway robbery," its alert says.

More than 47,500 people were killed in drug-related violence in Mexico between December 2006 and September 2011, according to the State Department. While most of those murdered were involved in criminal activity, innocent people were also caught in the crossfire, the State Department said. Mexican President Felipe Calderon declared a crackdown on cartels in late 2006.

The number of Americans reported murdered in Mexico last year was 120 -- up from 35 reported in 2007.

"We strongly advise you to lower your profile and avoid displaying any evidence of wealth that might draw attention," the alert says.

The travel warning urges Americans to defer nonessential travel to all or parts of the following 14 states: Chihuahua, Coahuila, Durango, Nuevo Leon, San Luis Potosi, Sinaloa, Sonora, Tamaulipas, Zacatecas, Aguascalientes, Guerrero, Jalisco, Michoacan and Nayarit.

Travelers should also exercise caution visiting all or parts of Baja California, Colima and Morelos, it says.

The previous U.S. travel warning issued for Mexico by the State Department, dated in April, advised American to avoid travel to all or parts of 10 states.