# The Great Migration and African-American genomic diversity

## TL;DR

This study explores how historical migration patterns, like the Great Migration, shaped the genomic diversity of African-Americans across the United States.

## Contribution

The study provides a comprehensive assessment of African-American genomic diversity using nationally representative genotype data.

## Key findings

- African ancestry is higher in the southern U.S. compared to the North and West.
- Relatedness patterns align with migration routes during the Great Migration.
- Ancestry-biased migration explains regional differences in genomic diversity.

## Abstract

Genetic studies of African-Americans identify functional variants, elucidate historical and genealogical mysteries, and reveal basic biology. However, African-Americans have been under-represented in genetic studies, and little is known about nation-wide patterns of genomic diversity in the population. Here, we present a comprehensive assessment of African-American genomic diversity using genotype data from nationally and regionally representative cohorts. We find higher African ancestry in southern United States compared to the North and West. We show that relatedness patterns track north- and west-bound routes followed during the Great Migration, suggesting that admixture occurred predominantly in the South prior to the Civil War and that ancestry-biased migration is responsible for regional differences in ancestry. Rare genetic traits among African-Americans can therefore be shared over long geographic distances along the Great Migration routes, yet their distribution over short distances remains highly structured. This study clarifies the role of recent demography in shaping African-American genomic diversity.