Lewis and Clark consulted with James Mackay on John Evan's map of the lower Missouri River, either at Camp DuBois or in St. Charles, Missouri, where Mackay lived..
James Mackay was born about 1759 in Arrichliney, County Sutherland, near the northern coast of Scotland. He immigrated to Canada around 1775, when he was just a teenager. Three brothers and an uncle has gone to the U.S. shortly before. There was a population explosion in Scotland at this time and a shortage of arable land. Growing up in Scotland in the eighteenth century would have prepared Mackay and others well for life in the Canadian and American wilderness. Northern Scotland had a rough, mountainous terrain and a frigidly cold climate.
Mackay participated in the fur trade . He traveled as far west as the Rockies by 1788 (see map). While trading in Canada for Robert Grant’s company, he ventured south as far as the Mandan Villages in modern-day central North Dakota.
James Mackay then worked for Donald Mackay’s (no relation) struggling company in Saskatchewan. Then he moved down into the United States. In New York he probably met a Spanish minister, Don Diego Maria de Gardoquito. The minister was impressed with Mackay's experience in the West and with his map. He recommend Mackay to colleagues in St. Louis. On his way to St. Louis, he met a Dr. John Rees (born Morgan John Rhys in Wales). Rees recommended he meet with John Evans about the theory that some western Indians may be Welsh speakers. Mackay arrived in Cahokia in 1791, where he became a trader. By 1793 he became a Spanish subject. He made contacts with Zenon Trudeau, who engaged him to explore the Missouri River in 1796 as commander of the expedition.
Just as Lewis and Clark used the Mackay-Evans map for their trip, Mackay used the 1795 map of the Missouri River made by the St. Louis surveyor general Antoine Pierre Soulard, whose map was based on word of mouth and shared knowledge among European fur traders such as Jean Baptiste Truteau. The Soulard map was detailed for as far west as the Mandan villages in North Dakota. Knowledge of land west of there was sketchy and often erroneous.
Mackay traveled on the expedition as far as the Maha villages. He gave detailed instructions to Evans to proceed to the Mandan villages and beyond, keep copious records and make a detailed map. Mackay stayed at Fort Charles (in modern day Nebraska) to work with Omaha Chief Blackbird to plan a gathering of tribes for the summer of 1796. The gathering was to impress and persuade the tribes to allow the Spanish companies to trade up the Missouri River and take over the trade that the British has established with those tribes. This gathering never took place, although Blackbird probably received numerous trade goods. Mackay spent the summer and fall instead exploring northeastern Nebraska, possibly on a buffalo hunt with the Omaha. His route is known from notes made on two maps (Perrin du Lac’s published map dated 1802 and a French manuscript chart in the papers of Joseph Nicollet, Library of Congress.
After the expedition was over, in his capacity of Commandant of St. Charles,
Mackay received a land grant of more than 46,000 acres, mostly in present-day
St. Charles and Lincoln counties north of St. Louis. He never registered some
of the land, and it passed into dispute or other ownership. In 1800, Mackay
married Isabella Long. They had ten children. Mackay worked as a surveyor
for Antoine Soulard, a judge and a justice of the peace. In 1803, he met with
Meriwether Lewis to discuss a copy of the Mackay-Evans Map that had been sent
to Lewis by Thomas Jefferson. In 1816, he was elected to the Missouri legislature
as a representative from St. Louis. He built the first brick house in St.
Louis in 1819. Mackay died in March of 1822 at age 63.