On the south side - they have almost nothing except the Mexican federal army. All the local law enforcement has been co-opted, politicians threatened, kidnapped or murdered frequently. Constant kidnappings for ransom. Lots of terrorist acts to intimidate everyone. Civilians have no one trustworthy to turn to.
Recently, an inter-cartel war broke out big time in Reynosa, the city with tons of factories and the source of lots of economic well-being for McAllen, the sister city. People stay inside after dark. The factories shut down during the gun battles. It seems like no-one can get this stuff to stop over there. Wealthier Mexicans are moving north of the border as fast as they can and McAllen is seeing a temporary boom from this, but if Reynosa becomes a ghost town due to the violence, a big economic driver for McAllen disappears.
In Just One Year, A Mexican City Turns Violent : NPR
You really wonder how long this can go on. Can the cartels just wipe each other out? Unfortunately the civilian casualties are high in such a scenario.