''Run of the mill'' meaning and origin. Phrasefinder
The mill in question was a weaving mill and the articles first called ''run of the mill'' were clothes. An early citation of that comes from an advert by Cook, Taylor Co. of Lowell, Massachusetts in The Lowell Daily Sun, December 1895: "Seconds and the run of the mill, but for all wearing purposes just the same as firsts at twice the price.