Road, rail, air and water transportation are all prevalent and important across Europe. Europe was the location of the world's first railways and motorways and is now the location of some of the world's busiest ports and airports. The Schengen Area enables border control-free travel between 26 European countries. Freight transportation has a high level of intermodal compatibility and the European Economic Area allows the free movement of goods across 30 states. Of all tonne-kilometres transported in 2016, 51% were by road, 33% by sea, 12% by rail, 4% by inland waterways, and 0.1% by air.