The first half of 2011 was the most deadly six-month period for U.S. citizens in Mexico over the past eight years, according to U.S. State Department data.

The statistics, compiled by Los Angeles’ La Opinión newspaper from the State Department's database, state that between January 4 and June 11 of this year, 65 Americans were killed in Mexico, a 300 percent increase from 2003. After Mexican President Felipe Calderón declared war on the country’s drug cartels in 2006, U.S. citizen deaths in its neighboring country rose dramatically. In 2007, 35 Americans were killed and last year this figure rose to 111.

The newspaper story noted that the U.S. statistics may be higher because the State Department only recorded deaths that were reported voluntarily. The U.S. statistics did not include deaths where Mexican authorities discovered a body, as in the case of the U.S. citizen found bound in an Acapulco apartment with a note from drug-traffickers attached to the body.

"It is an indicator of the trans-nationalization of fighting organized crime,” Dr. Octavio Pescador, the coordinator of UCLA's Latin American Institute, told La Opinión.

The majority of U.S. citizen deaths in Mexico were concentrated in the northern parts of the country, especially in the violence-plagued cities of Ciudad Juárez and Tijuana. Around a third of all U.S. deaths occurred in those two border cities.

Over one third of all U.S. citizens killed in Mexico in 2010, whose deaths were reported to the government, were killed in the border cities of Ciudad Juárez and Tijuana.The rate of drug-related killings in the border states of Nuevo León and Tamaulipas has increased dramatically over the past two years, according to La Opinión.

While the state department said in its latest travel warning that there is no sign that U.S. tourists have been targeted by criminal organizations due to their citizenship, it did advise Americans to be careful when traveling in Mexico due to the risky security situation related to the ongoing drug war.

“Resort areas and tourist destinations in Mexico generally do not see the levels of drug-related violence and crime reported in the border region and in areas along major trafficking routes,” The State Department said in its April warning.  “Nevertheless, crime and violence are serious problems and can occur anywhere. While most victims of violence are Mexican citizens associated with criminal activity, the security situation poses serious risks for U.S. citizens as well.”

Tourist areas, such as spring break hotspot Cancún and the Gulf of Mexico city of Veracruz, have seen their share of drug-related violence with authorities discovering eight bodies on a highway outside Veracruz earlier this week.

Despite the violence, Mexican officials told Fox News last year that tourism in the country has increased last year. According to Mexico’s Tourism Board, the number of international tourists visiting the country by plane increased 35 percent in June of 2010 compared to the same month in the previous year.

"We feel these numbers are evidence of the strength and quality of Mexico's destinations,” Mexico's Secretary of Tourism, Gloria Guevara, said in a statement.

Andrew O'Reilly can be reached at andrew.o'reilly@foxnewslatino.com or follow him on Twitter: @aoreilly84

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