Which region of the united states has the lowest elevation overall

Which of the following statements is accurate about the work done by southern slaves? after not being able to abolish slavery in the 1830s in virginia, the state banned slaves from doing work in tobacco fields. the leasing of slaves ended by 1800. slaves were prohibited from supervising white laborers. by the time of the civil war, about 200,000 worked in industrial-type occupations. the federal government used only ex-slaves to build public structures in the south.