In North America, it is present but tends to be less dominant than haplogroups A and C in many populations of the northern part of the continent.

This distribution pattern has been interpreted by geneticists as reflecting aspects of the demographic history of the Americas — the specific migrations and population movements that shaped the distribution of maternal-line diversity across the hemisphere.

The presence of haplogroup B in both North and South America, but at varying frequencies in different regions, suggests that it was part of the founding diversity of the Americas from early in the peopling of the hemisphere, and that subsequent population movements and demographic events distributed it unevenly across the continent.

Finding haplogroup B in an individual who died in Colorado approximately 8,800 years ago — in the interior of North America, at high altitude — contributes a specific data point to this picture.