Photos (2x2-inch negatives, Kodak Safety Film) by Cheryl(?) Riley / The Signal.
Update February 2020: Mike Preasmeyer, now of Placerville, identified himself as the boy pointing to the sign (center). Preasmeyer is retired from a 32-year career with the U.S. Forest Service as a wildland firefighter, including 15 years as a Type 2 Operations Section Chief. He started at Texas Canyon in the SCV, then spent 25 years with the Los Padres National Forest and retired out of the Klamath National Forest where he was a Division Chief. He says he decided to go into firefighting after his parents' home was lost in the 1970 wildfires.
According to Pamela Louise (Booth) Fulmer, now of Paso Robles, the boy in the V-neck, two to the right of Preasmeyer, is Rick Crooks. Pamela, who believes she was present that day, attended Mint Canyon's first first-grade class and on to the first sixth-grade graduating class with her brother, Al Booth.
April 1968 — Unidentified members of the student body at Mint Canyon School formally present a new monument sign to Dr. Ralph Bell, superintendent of the Sulphur Springs Union School District. The students conceived and donated the sign, which was installed near the highway.
"Because the school sets some distance off the road, the youngsters thought the sign would be appropriate." (The Signal, 4/24/1968, photo caption only).
Mint Canyon School opened September 10, 1963, at 16400 Sierra Highway. The previous Mint Canyon School burned down in 1947. Between 1947 and 1963, children in Mint Canyon attended Sulphur Springs School.
The (current) Sulphur Springs Union School District was organized September 1, 1944, when the original (1872) Sulphur Springs School District and the (2/12/1879) Mint Canyon School District united. (Source: The Signal, 2/16/1968, pg. 5.)
"Union" in a school district name refers to the union (combination, merger) of two or more school districts into one. It has nothing to do with labor unions and should not be conflated with "unified," which is a school district with both primary and secondary grades (K-12 or K-14).
9600 dpi jpegs. Signal Photo Archive, Santa Clarita Valley Historical Society collection.