A narrowboat is a particular type of canal boat, built to fit the narrow locks of the United Kingdom. The UK's canal system provided a nationwide transport network during the Industrial Revolution, but with the advent of the railways, commercial canal traffic gradually diminished and the last regular long-distance transportation of goods disappeared in 1970. However, some commercial traffic continued. From the 1970s onward narrowboats were gradually converted into permanent residences or as holiday lettings. Today, approximately 6000 narrowboats are registered as permanent homes on Britain's waterway system and represent a growing alternative community living in semi permanent moorings or continuously cruising.