The execution of El Monte school board member Agustin Roberto “Bobby” Salcedo in the Mexican state of Durango is a horrible reminder that Mexico’s drug violence does not belong to Mexico alone. It’s ours too. There is the fact that U.S. consumption drives the illicit narcotics trade, of course. But there is also the reality that social and business relationships binding the two countries have resulted in a border that cannot guarantee Americans protection from drug violence.

An estimated 1 million American citizens live in Mexico, and many more travel there each year. Families straddle the border, as do cities. Some cities do so literally, and in those, violence may cross north; others do so through their official and economic ties. Salcedo met his wife, Betzy, of Gomez Palacio, Durango, when she came to Southern California as an exchange student; he was past president of the sister city program between her hometown and his. They were visiting family for the holidays and went out for drinks with friends when Salcedo, 33, was abducted and killed along with five other men. Salcedo’s death is a tragedy for his family and community, and our hearts go out to them.

In Mexico, unfortunately, the killing is more commonplace and less shocking. More than 15,000 people are believed to have been slain in drug-related violence there during the last two years, and although the vast majority are believed to have been traffickers, police or military, the victims include a growing number of civilians: more than 400 women, 149 minors, three dozen government officials and at least a dozen journalists in 2009, according to Mexican media tallies. The December killing of drug lord Arturo Beltran Leyva in an operation that also took the life of a Mexican marine was followed within days by the slaying of the marine’s grieving mother, sister, brother and aunt.

Most of us think of violence as something that happens somewhere else -- or to someone else. In Mexico, the bloodshed has spread from traditional trafficking strongholds in Sinaloa and Chihuahua to Morelos, where Beltran Leyva was killed, and Tabasco, where the marine’s family was slain. In Durango, Betzy Salcedo told The Times’ Tracy Wilkinson that “you’re careful, you look around, but you never think this kind of thing can happen . . . to innocent people.” She and her American husband were having a good time one minute, and the next, “we were in the mouth of the wolf.” Sadly, Salcedo is unlikely to be the last American caught up in the brutality.