Mexico border crime problems
As with much else the news about Mexican border crime is often sensationalised. Yes , there are muggings, roberies etc . and they reflect the problems caused by large numbers of people from Mexico and Central America gathering in the frontier zone for the express purpose of trying to get into the USA. As can be expected such a collection of vulnerable people often carrying much of their meagre savings will also attract the nasty parasites who see a chance to make a killing, sometimes literally.Nearly all of the nastyness is suffered by these migrants, during their hazardous nighttime attempts to get into the "promised land". This phenomenon is also present along the southern border of Mexico where they sneek in from Guatemala .The other problem is the organized smuggling of drugs and these morons have been particularly violent recently, killing cops and anyone who tries to get in their way.
You as a tourist will have little real contact with these problems unless you go looking for trouble. Sure, go for a look at some of the problem areas in daylight, but get off the highway before dark. Observe the game of cat and mouse from the US side as INS agents patrol the fences or the Rio GRande banks, haul back busloads of detainees to be released in Mexico so they can give it another try.
Just be watchful of what you do, mind your manners ,travel in daylight and you will be fine.