In modern economic depressions, it's likely that economic failure will have a high rate of onset. If so, the result would be widespread and relatively unmitigated economic dislocation (as we have seen, a tightly coupled system can fail both quickly and broadly, faster than governments can respond). Further, this type of failure will naturally result in a delegitimization of government institutions and the revival of primary loyalties -- as in, people will naturally focus their loyalties on family, friends, community, etc that support them during tough times. This is the opportunity space for organizers of resilient communities.
Unfortunately, in many cases a shift to primary loyalties will not be a benign occurrence. They will be assigned to groups that are not only able, but willing to use violence to advance their objectives. As each new violent group forms, it will put pressure on adjoining areas to form violent groups of their own. One question that seems interesting is: how quickly will these violent groups propagate? The answer is very quickly, if we use current gang membership as the starting point.
Gangs are, for all intents and purposes, manufactured tribes that fill holes in governance and community networks. They use a synthetic culture to create a new primary loyalty -- common mythology, fictive kinship, religious interpretation, etc. (in short, anything that sets them apart from everyone else). Cohesion is maintained through a system of mutual defense, respect, and honor. So, by extension, warfare is conducted over the same issues: encroachment, disrespect, and slights to honor.
Gangs in the US
Current gang membership in the US is now estimated at more than 1 million people, a 25% increase over 2005 (see the FBI's 2009 report pdf). These members are divided into over 20,000 different gangs the composition of which falls into three buckets (a classic "Long Tail distribution"):
- Large gangs. A handful. Many small to mid-sized structured and unstructured groups connected via a common culture. Membership typically measure in the tens of thousands.
- Mid-sized gangs. Scores. Typically tightly structured groups with membership in the low hundreds or the low thousands. Typically over 350 members with a middle management (although more acephalous than hierarchical).
- Micro-gangs. Thousands. Lots of small gangs with membership in the single digits or tens.* Likely 5-12 members or 25-150 members (due to organizational constraints).