Although this is another undated issue, my guess would be February or April, 1941. The photos are all in color, which suggests a 1941 date rather than 1940, and I’ve seen the March, 1941 issue, which features Shasta Dam.
This issue features flowers: California poppies on the cover; Oregon rhododendrons and California balsam root on page 2, plum trees, tulips, and water lilies on page 3, cactus on page 4, and several more. They manage to get Mt. Hood, Mission Santa Barbara, and a Coast Daylight train behind the flowers. Apparently, flowers do not bloom in Nevada, New Mexico, Texas, or Louisiana, all states served by the Southern Pacific that are unmentioned in this brochure.