Liverpool is a city and metropolitan borough of Merseyside, England, United Kingdom along the eastern side of the Mersey Estuary. It was founded as a borough in 1207 and was granted city status in 1880. It is the fourth most populous British city, and third most populous in England, with a 2011 population of 466,400 and is at the centre of a wider urban area, the Liverpool City Region, which has a population of around 2 million people. Historically a part of Lancashire, the urbanisation and expansion of Liverpool were both largely brought about by the city's status as a major port. By the 18th century, trade from the West Indies, Ireland and mainland Europe coupled with close links with the Atlantic Slave Trade furthered the economic expansion of Liverpool. By the early 19th century, 40% of the world's trade passed through Liverpool's docks, contributing to Liverpool's rise as a major city.