Final answer:
The 'dominant group' in the United States refers to non-Hispanic whites, and while they are spread across all regions, the South has historically had a high percentage alongside a substantial African American population.
Step-by-step explanation:
The question asks about the regional distribution of the dominant group in the United States. In this context, 'dominant group' typically refers to the majority ethnic or racial group, which in the United States is non-Hispanic whites.
Based on census data, which shows a heavy concentration of non-Hispanic whites in various parts of the country, the dominant group can be found in significant percentages across all regions.
However, historically and currently, the South has had a high percentage of non-Hispanic whites alongside a substantial African American population.
The census map also notes large numbers of individuals of Mexican ancestry in the West, particularly in California and the Southwest, and a significant population in the Upper South that identifies as simply American.
For the best answer, more specific demographic data localized to each region would be necessary.