Perhaps a little more relevantly, though not as recently,

>It is estimated that at the beginning of the 20th century, up to 40% of blacks in the [United States] South were trapped in peonage.

...a number that, to my limited knowledge, remained at a steady level, particularly in Alabama, up until Bailey v. Alabama in 1911, (which abolished the state's illegal and loophole-y neo-slavery provisions), and after that did not decrease significantly until the signing of Circular 3591 on December 1941, which led to a rapid-fire series of arrests and prosecutions, yadda yadda, last black slave freed in October of 1942. Ignoring modern, more or less color-blind human trafficking, of course.

Very interesting topic, especially if you ignore the happy ending and remember that segregation persisted until 1964, and its effects persists to this day.