Milling was another local industry with Zimra H. Baxter, George W. Bradley, and Abraham Boswell building a grist mill. Later more mills were built and modernized, and Nephi's Gem and Snowflake flour became known throughout most of Utah. In 1917 R.C. and Robert Winn built a mill which was later purchased by the Hermanson family. In June 1991 it was destroyed by fire with a loss of more than $20,000 worth of inventory; however, the California partners who now own it are planning to rebuild.

When gypsum was found at the mouth of Salt Creek Canyon, plaster was made by grinding it between two rocks and cooking the powder. Later a grinding machine was obtained and a waterwheel installed which was powered by water diverted from Salt Creek. In 1889 the Nephi Plaster and Manufacturing Company was incorporated and the first mill was constructed. It survived two fires in the early 1900s and flourished to become the major employer in Nephi.