(NewsNation) — Americans are being warned not to travel to several states in Mexico because of the increased risk of crime and kidnapping.

The U.S. State Department reissued a travel advisory on Wednesday, recommending that U.S. citizens do not travel to six Mexican states: Colima, Guerrero, Michoacán, Sinaloa, Tamaulipas, and Zacatecas. The last state was added this year in the annual advisory.

The State Department advised travelers to reconsider plans to go to seven other states, including Baja California, home to Tijuana. U.S. workers there were told to shelter in place last week following a string of violence in which vehicles were set on fire.

U.S. Ambassador to Mexico Ken Salazar said in a statement the travel advisory underscores the binational work needed to improve security in Mexico.

“Without security, there is no prosperity,” Salazar said. “It is important to reaffirm our commitment to citizen safety by providing training and resources to Mexican justice and security institutions and deepening our cooperation. The United States will continue to work with our partners, friends and neighbors as we build a peaceful future together.”

He referenced the Bicentennial Framework, a plan outlined in January that seeks to improve cooperation between the U.S. and Mexico on public safety in the region. In July, Mexico also announced it would invest $1.5 billion in “smart” border technology to help stem the flow of migrants into the U.S.

For those traveling to Mexico, the State Department recommends a list of steps to stay safe, including:

• Keep traveling companions and family back home informed of your travel plans.
• Use toll roads when possible and avoid driving alone or at night.
• Exercise increased caution when visiting local bars, nightclubs, and casinos.
• Do not display signs of wealth, such as wearing expensive watches or jewelry.

Three Mexican states were upgraded to safer levels on this year’s advisory, according to Salazar’s statement: Nayarit, Mexico State, and Coahuila. All are in the department’s Level 2 advisory, in which Americans are urged to exercise increased caution.