In the 1920s before the Great Depression, California’s astounding growth in economy attracted millions of immigrant to southern California . Thanks to the increased automobiles ownership , the oil boom in the 1920s , the rapid development of electrical utilities , agriculture and other industries, this decade witnessed many major revolutions in business organization and manufacturing technology .
During the 1930s, the Great Depression made California’s economy plummeted like other countries, making 25 percent of all workers and 37 percent of all nonfarm California workers