This region lost the largest black population during the reverse migration.

Explanation:

African Americans from the rural South to cities of the North, Midwest and West

2 million rollerblades hppe this.

crop rotation kepy different plants in the soil instead of once constintly. when switching out plants you have different nutrients being absorbed at different speeds and different roots growing differently therfore the spoil and water flow have to adapt and carry fresh nutrients to carry the constant changes that were going on in the soil.