The significant migration movement in the U.S. during the 1930s was the Dust Bowl migration, where thousands of families, primarily from the Great Plains, left their farms due to severe drought and dust storms. This environmental disaster prompted many, particularly in Oklahoma and Texas, to travel westward to California in search of better living conditions and work. The migrants, often referred to as "Okies," faced economic hardship and discrimination but were part of a broader movement that reshaped demographics and contributed to the growth of agricultural labor in the Western states.