The pattern of growth of the United States electronics industry on each of the two coasts is decidedly different. In the years 1920 to 1940, while the large eastern firms controlled the electronics market, a small group of entrepreneurs laid the basis for the present electronics industry on the Pacific Coast. The background to and the growth of this industry can be viewed as a four-stage process-developing out of an area with a colonial economy controlled by eastern United States firms to the present mature position of the electronics industry. The first three stages are discussed in this paper. Several of the most important companies in northern Calfornia have been selected for emphasis and these include both wireless and electronics companies. Stress is placed on the vertical and horizontal time relationships among these companies and the technology they relied on and modified.