For a century and a half the Great Lakes region and Mississippi River system, and all Native peoples who flourished there, were the focus of French explorers and missionaries. The English on James Bay set limits to the north, and their trading posts on the upper Hudson River set limits to the south.

Southern Ontario is one of the first inland areas to be explored, lying beyond the bigger rivers and water bodies (interactive map: French Exploration 1603-1751 -> map layer: Primary routes, 1603-1626). The shortcut between Lake Ontario and Georgian Bay has, over the years, attracted canal promoters, railway builders, and highway planners. From the 1630s to the 1660s French exploration stalled against English pressure; Quebec was briefly in English hands in the 1630s and again in the 1650s (map layer: Primary routes, 1627-1656).

French exploration resumed after 1660, coinciding with a major settlement initiative in the St Lawrence Valley. By the 1680s Frenchmen had crossed from the western Great Lakes into the Mississippi system at two points: the head of Green Bay on Lake Michigan and the western tip of Lake Superior. They had also reached James Bay overland from three places -- Lac Saint-Jean, the Ottawa River, and Lake Superior -- just as the British Hudson’s Bay Company was establishing itself on Hudson Bay (map layers: Primary routes, 1657-1680 and 1681-1751).

Frenchmen would encounter the English on James Bay, just as they had done half a century earlier at Albany, New York (map layer: Forts or Trading Posts). Expansion funneled westward, reaching the Missouri River and Lake Winnipeg by the middle of the 18th century. New Orleans, at the mouth of the Mississippi, was established in 1700, completing the French Crescent from the Gulf of St Lawrence to the Gulf of Mexico; it surrounded the thirteen English colonies. The static map: Delisle map of 1752 reminds us that the Pacific Ocean remained an underlying goal, however, and any cartographic trick to bring it nearer the east was welcomed.

Acadia (later-day Nova Scotia and New Brunswick) is not recorded as being explored. It appears that coastal activity had been sufficient to give a clear idea of what lay inland, and exploration was an unheralded part of the routine of Acadian farmers on hunting or fishing expeditions.