Final answer:
The largest number of counties where African people are the numerical majority is in the Southern United States' Black Belt region, which continues to reflect the historical concentration of African American populations stemming from the slavery era.
Step-by-step explanation:
The region of the United States with the largest number of counties where African people are the numerical majority is known as the Black Belt in the southern United States. This area covers a swath of territory stretching across the Southeast and portions of the Deep South. Historical maps, like the one issued by the US Coast Guard from 1860, reflect the high concentration of slaves in this region, a legacy that has persisted to the present day with a significant African American population.
Even following the Civil War and the abolition of slavery, the demographic distribution did not significantly shift. Freed slaves often remained as agricultural workers in the South, maintaining the concentration of African Americans in the region. As of the 2000 census, this constellation of majority African American counties continued to be heavily concentrated in the South, particularly in the Upper South. States such as Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, South Carolina, and Texas make up the bulk of the Deep South, whereas the most substantial free Black populations before the Civil War resided in the upper southern states.
The specifics of this demographic trend could be attributed to various historical, social, and economic factors, including the precedent set by the slavery-based agricultural economy and subsequent patterns of segregation and marginalization.