Liverpool is on the eastern side of the Mersey Estuary and historically lay within the ancient hundred of West Derby in North West England's 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 general cargo, freight, and raw materials such as coal and cotton, merchants were involved in the slave trade. In the 19th century, Liverpool was a major port of departure for English and Irish emigrants to North America. It was home to both the Cunard and White Star Line, and was the port of registry of the ocean liners RMS Titanic, RMS Lusitania, RMS Queen Mary, and RMS Olympic.