Liverpool is on the eastern side of the Mersey Estuary, and historically lay within the ancient hundred of West Derby in the southwest of the county of Lancashire. It became a borough in 1207 and a city in 1880. In 1889, it became a county borough independent of Lancashire. Its growth as a major port was paralleled by the expansion of the city throughout the Industrial Revolution. Along with handling general cargo, freight, and raw materials such as coal and cotton, the city merchants were involved in the Atlantic slave trade. In the 19th century, it was a major port of departure for Irish and English emigrants to North America. Liverpool was home to both the Cunard and White Star Line, and was the port of registry of the ocean liner RMS Titanic, the RMS Lusitania, RMS Queen Mary, and RMS Olympic.