The rugged and threatening natural environment of the sixteenth and seventeenth centuries made a compelling case for improving the health system in the eighteenth and nineteenth centuries. During the 1500s the North American continent was colonized by Spanish, French, Dutch, and English explorers. Multiple trading posts were established along the coastlines and rivers. By the late 1600s some European settlements had spread inland. Most Spanish and Portuguese efforts focused on exploration, land claims, and get-rich-quick schemes. Seventeenth-century life in North America was characterized by European colonists surviving precariously in dangerous environments, scratching out an existence in strange lands. Health systems were crude and sparse and were operated with a limited supply of physicians.