Final answer:
The Rh blood group is classified based on the presence or absence of the Rh D antigen. In the United States, about 85 percent of Americans are Rh positive (Rh+), while 15 percent are Rh negative (Rh-). There is no specific ethnicity that has a higher rate of Rh negativity compared to others.
Step-by-step explanation:
The presence or lack of a second erythrocyte antigen known as Rh determines the Rh blood group classification. Rh-negative people are those who do not have the Rh D antigen. Roughly 85% of Americans identify as Rh positive (Rh+), with the remaining 15% being Rh negative (Rh-). Therefore, there isn't one ethnic group that is more Rh negative than another in terms of ethnicity.