A North American lattice of trade corridors where freight distribution is coordinated by major gateways (container ports) and inland freight distribution clusters (IFDC) has emerged in recent decades. While gateways and IFDCs are significant markets, they also command distribution within the market areas they serve and the corridors they are connected to. They thus have a significant concentration and logistics and intermodal activities. The extent of the market area of an IFDC is mainly a function of the average length of domestic truck freight haul, which is around 500 miles (800 km). Like many segments of the North American economy and territory, globalization and integration processes, namely NAFTA, have impacted the nature and function of continental production, consumption, and distribution. For international trade, the gateways of this system are major container ports along coastal areas from which long-distance trade corridors are accessed. About a third of the American trade took place within NAFTA, mainly through land gateways (ports of entry) that are gateways because they are obligatory points of transit commanding access to the United States. For truck and rail flows, virtually no intermodal activities occur at land gateways, although several distribution centers are located near borders and along corridors. Laredo and El Paso, Texas, and the Detroit / Windsor complex are notable exceptions with significant freight distribution activities linked with crossborder trade.