Below is a part of a record from Appointments of U.S. Postmasters, 1832-1971, covering San Diego County, from the database of the National Archives and Records Administration:

It shows that a post office named Helix was created on February 5th, 1885 with Rufus K. Porter as postmaster.

As was often the case in the county in those days, this post office was on a ranch owned by Mr. Porter, who’d acquired some acreage in 1865 in the area which we today know as Spring Valley.

According to the account most accepted by historical researchers, the name Helix was attributed to Porter himself, inspired by a discovery on the trail leading from his ranch up a certain local mountain. As Porter’s daughter Rufina Porter Crosby stated in a memoir in the 1930s, “In traveling over the mountain one day he picked up some snail shells, and in Latin Helix means snails-thus the name.”

Helix aspersa was at that time the Latin name for the brown garden snail, today called Cornu aspersum. Porter clearly chose to call both his ranch and the mountain Helix.

In 1909 the name of the post office was changed to Spring Valley. The mountain’s name has remained Helix to this day.

In addition to the aforementioned National Archives database, sources for this post included the book San Diego County Place Names A to Z by Leland Fetzer, historic San Diego newspapers, and Featured Creatures, a database cooperatively run by the University of Florida’s Entomology and Nematology Department and the Florida Department of Agriculture and Consumer Services Division of Plant Industry.