On 29 October 1863 county surveyor James Martineau drew up a plot of Mendon City, laid out into nine square blocks with a central square. Each block was divided into eight lots, each ten rods wide and twenty rods long, with six-rod-wide streets. In the spring the log houses were moved to the outer lots and orchards were planted. George Thurston and Kelsey Bird built a grist mill on Gardner's Creek. Construction was started on rock homes and on a 28-by-45-foot native rock church, designed by George Baker.

In 1869 commerce was stimulated by the establishment of a federal land office in Utah and the joining of the transcontinental railroad thirty-one miles west of Mendon. A ZCMI branch was organized in Mendon with Willie as general manager; and Albert Baker built a hotel with local rock. Henry Hughes began a long tenure as local bishop. On 12 February 1870 the Legislative Assembly passed an act incorporating Mendon City; the effective date was 1 April 1870. George Baker was elected first mayor.

Utah Northern Railroad started construction in 1871 on a roadbed over Collinston Hill into Mendon; the depot was on the town square. The town's population was 427. In 1873 the rock Mendon co-op building was erected. Apostle Erastus Snow organized a twenty-member united order in Mendon; however, it lasted only a year. After 1889 Hyrum Richards operated the store. John Anderson opened another store in 1901.