According to research in an article for the St. Charles County Post of March 31, 2005, James Mackay came to the United States from Scotland as a teenager in the 1770s. He was a state legislator, a judge, a surveyor and the third commandant of the district of St. Charles from 1801-1804. Mackay explored and mapped the Missouri River before Lewis and Clark arrived; the maps and Mackay's advice were used by explorers. Mackay settled in St. Charles and in 1800 married Elizabeth Long.

Mackay's house was torn down in 1950.

(excerpts from article, St. Charles County Post, March 31, 2005, by Valerie Schremp Hahn)