As one of the world's busiest rivers the Rhine carries about 300 million tons of freight annually, upriver and down, between Switzerland and the Dutch ports on the North Sea. Heavy shipping traffic on the Rhine, including ocean vessels reaching Mannheim and barges reaching Basel, has been an integral part of the Rhine valley landscape for the past 150 years. But a bounty of commercial shipping on the Rhine has not always been part of the river's history. Despite the Rhineland's growing population and increasingly productive economy at the end of the early modern period, long-distance shipping activity along the river gradually declined during the seventeenth and eighteenth centuries. River commerce revived and expanded only in the early nineteenth century, stimulated in part by new developments in transportation technology, business organization, industrial development, and an unprecedented civil engineering assault on the river's natural contours. These material components of the nineteenth century transportation revolution as it unfolded along the Rhine are generally well known.