North Carolina windmills were of the "post mill" type --frame rectangular sheds built atop a single post some twenty or thirty feet off the ground. The entire structure revolved on the post and was manipulated by a tail post that reached from the building to the ground some seventy feet away. A wheel attached at the ground end of the tail pole ran in a track. Thus, the mill could be positioned to catch the prevailing winds.

The rotation of the fans turned a huge assembly of wooden gears inside the structure, which in turn moved the stones that crushed the grain.

The speed of the four fans was controlled by sails that covered their surface. The sails were furled to accommodate wind velocity, in much the same way that sails are used on boats. Regulation of the fan revolutions was important to the quality of meal produced. Too much speed on the stones scorched the grain and ruined it.

Mills were used for grinding wheat and corn and for pumping water. The former type were primarily located north of Onslow County and the latter south of Pender County. The mills of New Hanover and Brunswick Counties were often employed in the production of salt.

Post mills were simple and straightforward structures that could be easily built from available materials. If a location proved unprofitable, they were frequently loaded onto wagons and hauled to new sites. The Moravians at Bethabara (now part of Winston-Salem) built and transported a mill to Governor William Tryon's estate at Russellborough in 1767.

Wealthy planters such as Governor Tryon had their own mills for use exclusively on their estates. These were known as "plantation mills." Most mills, however, were "custom mills," operated for the general public, from whom the owner extracted a toll in kind.