Born in Stornoway Scotland in 1764, Alexander Mackenzie moved to New York with his family in 1774. He was schooled in Montreal and by the age 15 was employed as a clerk with the trading company Finlay, Gregory & Company. The firm was later absorbed by the North West Company. Mackenzie became a partner in the NWC and in 1788 was put in charge of the Athabasca region.

Mackenzie set out from Fort Chipewyan in early summer of 1789 with a team of voyageurs, their wives, and a native guide. He hoped to find the Northwest passage and claim new territory for the North West Company. The team followed a large river west from Great Slave Lake and by mid-July had reached the Arctic Ocean.

Though MacKenzie had called the place "Disappointment River", it was later named the "Mackenzie River" in his honour.

In 1791 Mackenzie traveled to England to learn more about astronomy and cartography. He returned to Canada in the spring of 1792 with new skills and instruments, eager to continue his explorations.

On June 12,1792, his team became the first European explorers to cross the Continental Divide and after treking overland for more than two weeks, Mackenzie and his team reached Bella Coola on the Pacific Ocean. Mixing vermilion paint with grease, Mackenzie wrote on the rocks of the Dean Channel shore:

Alexander Mackenzie, from Canada, by land
the twenty-second of July,
one thousand seven hundred and ninety-three


And so, Alexander Mackenzie became the first person to cross the North American continent and find a pass through the Rocky Mountains.

Mackenzie was knighted by King George III in England in 1802. He became a member of the Legislative Assembly of Lower Canada from 1804 to 1808 and in 1812 married and moved to Scotland, where he died in 1820 of Bright's disease.