Prior to economic integration processes, the development of national transportation networks supporting national flows was the priority. Transborder linkages and flows tended to be underdeveloped, particularly because of trade policies and national infrastructure investment strategies. Economic integration and trade facilitation obviously promote transborder flows, which may be accompanied by the development of new linkages to support them as well as new gateways (ports on entry). The Canadian / American border is a good example of the impacts of economic integration (NAFTA) on transborder trade flows, with the north/south component growing substantially. The European Union also has a comprehensive strategy called the Trans European Transport Networks, aiming to improve pan European connectivity over highway, railway, air, and canal systems.