TIJUANA – The U.S. State Department once more warned Americans about the dangers of traveling to Mexico, particularly to the northern border region, where international organized crime has eroded the quality of life and "armed confrontations occur unpredictably."

The travel warning has been issued every year for several years as drug cartels battle for control of key smuggling routes to the United States and the Mexican government challenges them.

The violence has reached record levels in cities such as Monterrey. But in Baja California the deadly violence has dropped dramatically in the last two years, with most murders now involving street-level drug dealers.

In fact, public officials frequently cite "the Tijuana case" as an example of how a coordinated effort by authorities in the three levels of government has controlled organized crime.

The warning comes weeks before one of the busiest travel periods of the year, when thousands of Americans flock to resorts for spring break. Tourism has gradually rebounded in last few years in Mexico but the alert is sure to re-ignite fears in that sector that Americans will again opt to go elsewhere.

U.S. State Department noted in its web site that "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."

However, the travel warning was being issued "to inform American citizens about the security situation in Mexico." It names Tijuana and 20 other cities, particularly in northern Mexico, as being the most violent in that country.

"We urge you to postpone traveling in the areas noted in this warning and exercise extreme caution when traveling to the border," the warning said.

The alert said that the number of U.S. citizens killed in Mexico increased from 35 in 2007 to 120 in 2011, 34 of them in Baja California.

"You should be careful in this northern state, particularly at night," the alert read. "Transnational organized crime continues to carry out targeted murders in Baja California."

The warning cited the figures issued recently by the Mexico's Attorney General: 47,515 people killed in the drug-related violence from Dec. 1, 2006 to Sept. 30, 2011.

Confrontations between cells of rival gangs or with authorities have occurred in pueblos and cities across Mexico, especially in the border region, the warning said. Shootouts have occurred in broad daylight and on streets and other public places.

The alert said that in some of these incidents, American citizens were temporarily trapped and unable to leave.

Auto theft and armed assaults are a serious problem in the border region, as well, and U.S. citizens have been killed in these types of crimes, the alert said.

"The growing number of kidnappings and disappearances in all of Mexico is of particular worry. Mexican citizens as well as foreigners have been victims," the alert said. "In addition, local police officers have been implicated in some of these incidents."

About Tijuana, the alert said that battles between groups of criminals have increased and have resulted in numerous murders in areas frequented by American citizens.

"Shootouts, in which innocent people have been wounded, have occurred during the day in the entire city. In one of those incidents, a U.S. citizen was shot and gravely wounded," the alert said.

However, with the exception of the armed attack on a house in an eastside neighborhood Jan. 28, in which five males were shot to death, including a 13-year-old U.S. citizen, Tijuana authorities have not logged shootouts in public places nor "numerous murders" in tourist zones, as the warning said.

Murders have decreased in the city from 843 at the peak of the drug violence in 2008 to 476 last year. The majority has occurred in the city's outer neighborhoods and involves disputes among drug dealers. In January, state authorities reported 46 homicides, 11 less than the same month last year.

In addition to Tijuana, the U.S. alert cited violence associated with drug trafficking in Ciudad Juárez, Chihuahua, Coahuila, Durango, Monterrey, San Luis Potosí, Mazatlán, Nogales, Puerto Peñasco, Matamoros, Nuevo Laredo, Reynosa, Tampico, Zacatecas, Aguascalientes, Manzanillo, Acapulco, Morelia and Nayarit, among others.

omar.millan@sandiegored.com