During the seventeenth and eighteenth centuries a British Atlantic world took shape with the colonisation of North America and the West Indies. By 1775 the British Empire in the Americas covered 88,803 square miles and contained a population of 8.6 million. Each of the British American settlements was originally based around ports and harbours, which served as nodal points for a maritime economy. North American and West Indian ports were connected to British ports through shipping, trade, and the movement of people across the Atlantic. Underpinned by a mercantilist framework in the form of various Navigation Acts, through which goods were largely required to be traded within the British Empire, ports and their merchants in Britain and British America had a pivotal role in the expansion of seaborne commerce for both Britain and her colonies. Smaller ports provided shipping points for ships to enter, transfer cargoes and receive crew, payments and refreshment. Larger ports, with waterborne and overland connections linking up with productive hinterlands, served as powerhouses of an intricate web of trading connections across the Atlantic that connected productive areas for raw materials and agricultural resources with centres of consumer demand.