A four-part series by Ronald Campbell of The Orange County Register describes California’s extraordinary dependence on immigrant labor. Immigrants comprise a third of the state’s workforce a higher proportion than any other state and almost any developed economy. They dominate lower-paid jobs but also play huge roles in technology and health. The Register analyzed nearly 40 years of census data from the Public Use Microdata Series to report the story. The series continues through October 1 and will investigate the failure of the federal government’s 24-year campaign to deny illegal immigrants work; explain the costs and benefits of immigration to the larger public; and explore alternatives for fixing the nation’s broken immigration system.