quality:correction, structural:summarization
History

For most of history, transport by ship – provided there is a feasible route – has generally been cheaper, safer and faster than making the same journey on land. Only the coming of railways in the middle of the 19th century and the growth of commercial aviation in the second half of the 20th century have changed this principle. This applied equally to sea crossings, coastal voyages and use of rivers and lakes.

Examples of the consequences of this include the large grain trade in the Mediterranean during the classical period. Cities such as Rome were totally reliant on the delivery by sailing and human powered (oars) ships of the large amounts of grain needed. It has been estimated that it cost less for a sailing ship of the Roman Empire to carry grain the length of the Mediterranean than to move the same amount 15 miles by road. Rome consumed about 150,000 tons of Egyptian grain each year over the first three centuries AD.

Until recently, it was generally the case that a ship represented the most advanced representation of the technology that any society could achieve.