Final answer:
The chart depicts the increase in the enslaved population in the South compared to the northern states. The expansion of territory and increase in the free population in the South contributed to this difference. This factor led to the formation of a regional identity based on a strong agricultural economy reliant on enslaved labor.
Step-by-step explanation:
The regional difference depicted in the chart is the significant increase in the enslaved population in the South between 1790 and 1810, compared to the other northern states.
One important factor that contributed to this difference is the expansion of the South's territory and the increase in the free population during that time. The South went from a region of four states to six states and three territories, which provided more land for agriculture, including cotton plantations that relied heavily on enslaved labor.
This factor contributed to the formation of regional identities by establishing a strong agricultural economy in the South that heavily depended on slave labor. Slavery became deeply entrenched in the Deep South and was considered essential for economic prosperity, creating a distinct cultural and social identity in the region.