But in other ways the two cities are worlds apart these days.

El Paso still enjoys its status as one of the safest cities in the United States, while Juárez, a city of 1.5 million that has always been rough, has become a battleground for drug cartels. More than 1,550 people were killed there in drug wars last year.

Worse, other violent crimes  carjacking, extortion, armed robbery  have surged as the beleaguered authorities struggle to respond to daily gun battles.

“It’s strange to be the third-safest city in the United States right next to a war zone,” said Mayor John Cook of El Paso, as he gazed at the ramshackle neighborhoods of Juárez.

Yet what is happening on the other side of the border  a vicious turf battle prompted by Mexican government efforts to crack down on the cartels  is taking its toll here in myriad ways. Americans have cut back on visiting their relatives in Mexico, and Mexicans, too, venture to the American side in smaller numbers, either because they are afraid to leave their homes at night or because they lack money.

The local public hospital in El Paso has treated 48 people wounded in gun battles in Mexico in the last year, and law enforcement officials in the United States spend much of their time trying to figure out how to prevent the violence from spilling over into their jurisdictions.