Between the 1740s and 1820s eastern explorers reached the Cordilleran mountain ranges. About 1800 they finally broke through to the Pacific Ocean at Bentinck Arm and at the mouths of the Fraser and Columbia Rivers. There they found signs of decades of coasting activity by British, Spanish and Russian mariners.

At the same time as Hudson’s Bay Company traders were approaching the foothills of the Rocky Mountains from the east, mariners from Russia, Spain and Great Britain were starting to make coastal sailings along the Pacific Ocean shore, between Oregon and the Aleutian Islands (map: Exploration of the Far West, 1741-1821 - data layer: Primary routes, 1741-1784). Exploration of the fiords of today’s British Columbia coast and Alaska panhandle intensified in the last quarter of the eighteenth century, and in 1793 Alexander Mackenzie, a Montrealer, reached the head of one of those fiords at Bella Coola. (data layer: Primary routes,1785-1794) He thus completed the land crossing of America begun some two centuries earlier.

Mackenzie’s trip northward, down the Mackenzie River to its mouth on the Arctic Ocean, proved at the time to be a dead end; despite having reached the open ocean, he had no means of sailing upon it. Within a generation, however, ships were heading for the same place, the Beaufort Sea, making their approach from Lancaster Sound or the north side of Hudson Bay. (data layer: Primary routes,1813-1821) After nearly two centuries, Great Britain once again was actively seeking the Northwest Passage.

Meanwhile, aggressive activity by Montreal traders was leading to a thorough understanding of the geography of the western plains and intermontane regions. (data layer: Primary routes,1795-1812) By activating the modern place names layer, readers may see the irrelevance of the newly established border (in 1818) with the United States. American explorers and traders, passing up the Missouri River, added their understanding to the Oregon and Columbia River Country.

The intricacies of the Pacific coast and of the systems of mountain ranges were far beyond the capacity of the map-makers of this period. (static maps) Those features are little more than symbolic.