Why have gang-related crime rates in San Diego been surging?

Citing San Diego Police statistics, the Los Angeles Times has reported a 20% surge in gang-related crimes in San Diego in the first half of 2019, compared to the same period in 2018. During the same intervals, the number of gang homicides doubled from five to ten.

There doesn't seem to exist a published explanation for this development. States the Los Angeles Times:

It’s unclear what is behind the sudden surge in gang crime. Officials at the San Diego Police Department did not attribute the increase to a gang war, but acknowledged violence between rival gangs had intensified over the summer.

A plausible if not likely explanation is that violence in San Diego is an extension of turf wars between Mexican drug cartels in Tijuana.

Chicano street gangs in San Diego and the rest of California

In California, Mexican-American criminal organizations are divided into two rival hierarchies, with central command for each of those two located in federal and state correctional facilities. It's as if penitentiaries are “palaces” for their “nobles”.

The Mexican Mafia is the most powerful gang within the California prison system; most Chicano street gangs in Southern California pay tribute to the Mexican Mafia. These loosely-affiliated street gangs are called Sureños (southerners). Nuestra Familia is the prison organization for Chicano gangs based in Northern California. Latino street gangs north of Bakersfield and Fresno are called Norteños; they pay tribute to Nuestra Familia.

U.S. street gangs and Mexican cartel distribution networks

The Logan Heights Gang is a Sureño street gang based in Southeast San Diego. A December 2000 Drug Threat Assessment published by the U.S. Department of Justice reported that the Mexican Mafia controls a portion of the drug distribution in Southern California through control of street gangs like the Logan Heights gang.

Citing an unclassified U.S. Drug Enforcement Administration intelligence report, Univision described in December 2016 how Mexico's Sinaloa Cartel, under the control of Joaquín 'El Chapo' Guzmán, had consolidated dominance over narcotics distribution in California and other important U.S. regions. In that Univision report, author Gabe Morales said the Sinaloa Cartel had spread in California through the Mexican Mafia, under an agreement reached between leaders of those two organizations while serving time in U.S. prisons.

Univision added that the Sinaloa Cartel's main competitor, the Jalisco New Generation Cartel (CJNG), had also brought shipments to California and had established a strong presence in Orange, Imperial and Sonoma Counties, as well as cities in other U.S. regions.

The Tijuana/Baja California - San Diego/California plaza

Congressional Research Service report R41576, Mexico: Organized Crime and Drug Trafficking Organizations, reviews recent turf struggles in Tijuana.

The Arellano-Félix Organization, or Tijuana Cartel, historically controlled the drug smuggling route from Baja California to southern California. This Tijuana-based “tollgate” organization was infamous for brutally controlling the Tijuana drug trade in the 1990s and early 2000s. The Mexican and U.S. governments took vigorous action against the drug trafficking organization in the early 2000s, with the arrests and killings of the five “Arellano Felix” brothers involved in the drug trade — the last of whom was captured in 2008.

In 2008, Tijuana became one of the most violent cities in Mexico, as the Arellano-Félix Organization (AFO) split into two competing factions, one of which reportedly allied with the Sinaloa Cartel. Further contributing to the escalation in violence, other cartels sought to gain control of the profitable Tijuana/Baja California - San Diego/California drug trafficking turf, or plaza.

The Univision report included the following observation from Timothy Massino, speaking from the DEA office in Los Angeles: Whoever controls the routes going up to Tijuana rules whatever happens in southern California, especially Los Angeles, which is a big transition area for drugs sold in the (rest of) United States, and which is controlled by the Sinaloa cartel.

While some observers believe the Sinaloa Cartel was able to gain control of the Tijuana/San Diego smuggling corridor, the Arellano-Félix Organization appears to have maintained control of the plaza through an agreement made with Sinaloa leadership, with Sinaloa and other trafficking groups paying a fee to use the plaza.

Meanwhile, violence in Tijuana rose to more than 100 murders a month in late 2016, with the uptick in violence attributed to the Sinaloa slugging it out with its main rival, the Jalisco New Generation Cartel (CJNG). Led by Nemesio Oseguera Cervantes (“El Mencho”), the CJNG apparently has taken an interest in both drug trafficking within Tijuana and cross-border trafficking into the United States. Some maintain the resurgence of violence in Tijuana and the spiking homicide rate in nearby Baja California Sur are linked to an alliance forged by the CJNG with remnants of the Tijuana Cartel. In 2018, Tijuana was the Mexican city with the highest number of homicides, with 2,246, amounting to a homicide rate of 115 per 100,000.

Conclusion

The above review of turf wars in Tijuana was to suggest, by presenting circumstantial evidence, that the surge in San Diego gang violence has resulted from an expansion of Mexican cartel wars northward into U.S. territory.