Agricultural work declined during the Great Depression of the 1930s, and many African Americans continued to leave in the Great Migration north to find other work. In October 1930, oil was discovered in Henderson, Texas, near Kilgore. Suddenly, the county economy was booming, and the East Texas Oil Field attracted so many workers that county population increased by more than 500% by 1940. Growth stabilized, but oil has continued to be important. County demographics changed as other workers were attracted to the area. In the early 21st century, slightly less than 20% of the population is African American.