Liverpool is a city in North West England, with an estimated population of 491,500 in 2017. The local authority is Liverpool City Council, the most populous local government district in the metropolitan county of Merseyside and the largest in the Liverpool City Region. Liverpool is on the eastern side of the Mersey Estuary, and historically lay within the ancient hundred of West Derby in the south west of the county of Lancashire. It is also the home of two Premier League football clubs, Liverpool and Everton, matches between the two being known as the Merseyside derby. The Liverpool Maritime Mercantile City includes the Pier Head, Albert Dock, and William Brown Street. The word "Scouse" has also become synonymous with the Liverpool accent and dialect. Liverpool City Region Combined Authority. The original street plan of Liverpool is said to have been designed by King John near the same time it was granted a royal charter, making it a borough. In 1699 Liverpool was made a parish by Act of Parliament, that same year its first slave ship, Liverpool Merchant, set sail for Africa. However, as the Dee began to silt up, maritime trade from Chester became increasingly difficult and shifted towards Liverpool on the neighbouring River Mersey. As trade from the West Indies, including sugar, surpassed that of Ireland and Europe, and as the River Dee continued to silt up, Liverpool began to grow with increasing rapidity. The first commercial wet dock was built in Liverpool in 1715. By the start of the 19th century, a large volume of trade was passing through Liverpool, and the construction of major buildings reflected this wealth. In 1830, Liverpool and Manchester became the first cities to have an intercity rail link, through the Liverpool and Manchester Railway.