A custom house or customs house was traditionally a building housing the offices for a jurisdictional government whose officials oversaw the functions associated with importing and exporting goods into and out of a country, such as collecting customs duty on imported goods. A custom house was typically located in a seaport or in a city on a major river, with access to an ocean. These cities acted as a port of entry into a country.
Due to advances in electronic information systems, the increased volume of international trade, and the introduction of air travel, the term "custom house" became a historical anachronism. There are many examples of buildings around the world that were formerly used as custom houses but have since been converted for other uses, such as museums or civic buildings.[example needed]
In the United Kingdom, since 1386, the phrase "custom house" has been in use over the term "customs house". This was after the City of London's Custom House was erected at Wool Wharf in Tower Ward, to house just the officials overseeing the Great Custom on Wool and Woolfells. The singular form was used even though in later years the City of London's Custom House served as the workplace for other customs officials as well.