Two ‘Tri-Border’ areas (TBAs) in South America are significant contributors to the global illicit economy. The first encompasses Argentina, Brazil, and Paraguay, whereas the second lies between Bolivia, Peru, and Chile. These TBAs are crucial hubs for various criminal activities including drug trafficking, money laundering, and smuggling. Organised criminal networks in both regions are highly sophisticated and employ a vast range of tactics to evade law enforcement and regulatory oversight. These tactics include sophisticated techniques such as the use of hidden compartments in vehicles, chemical camouflage, exploitation of legal trade routes, use of encrypted communication technologies, use of front companies to conceal illicit activities, and complex techniques of money laundering and corruption. Illicit transport networks in the TBAs are often involved in various transnational criminal activities and are highly interconnected with wider global illicit flows. This chapter touches upon how these flows have been remodelling, adapting, and self-regenerating to counter both the states’ response to these crimes, as well as the ever-changing socio, political, and economic environment. Furthermore, it explores the dynamics of how these flows converge, intersect, and contribute to other illicit networks worldwide, highlighting, in its conclusion, the need for coordinated international efforts to combat transnational criminal activities.