From Michigan Place Names
Iosco County: the village began as a flag station on the Detroit, Bay City & Alpena Railroad in 1884. It was called Emery Junction and was given a post office of that name on March 21, 1904 with Quincy Martin as its first postmaster. The National Gypsum Company opened a quarry here in 1925 and the name of the village was changed to National City in 1926 [Lawrence H. Jordan, PM; GSM 1885; PO Archvies)
From Michigan County Atlas
A flag station here on the D.B.C. & A. Railroad (1884) became an important railroad center from about 1890-1928, named ENIERY JUNCTION, and was given a PO. of that name in 1904. The National Gypsum Company opened a quarry here in 1925 and the name of the village was changed to National City the next year.