Scottish: habitational name from Buchanan, a place near Loch Lomond, perhaps named with Gaelic buth chanain ‘house of the canon’.
FOREBEARS The name Buchanan was brought independently to North America from Scotland by several different bearers in the 17th and 18th centuries. George Buchanan came to MD in 1698.James Buchanan (1791–1868), 15th President of the U.S. (1857–61), was born near Mercersburg, PA, the son of a successful land speculator and store keeper, who had emigrated to PA from Scotland in 1783. The surname originated in the 13th century when the place name Buchanan was taken as a surname by Gilbrid McAuslan, head of a cadet branch of the clan McAuslan.