Fusarium wilt is an important and widespread disease of cotton (Gossypium hirsutum L. and Gossypium barbadense L.) caused by several races and genotypes of Fusarium oxysporum f. sp. vasinfectum W.C. Snyder & H.N. Hans (FOV). A two-year survey (2012-2013) was conducted to assess the distribution of the fungus, and in particular FOV race 4, throughout the United States (U.S.) Cotton Belt. Partial sequences of the translation elongation factor (EF-1α) region of FOV cultured from symptomatic cotton plants were compared to a database of sequences of known genotypes. Five nominal races of FOV, races 1, 2, 3, 4, and 8, and four previously recognized southeastern genotypes, LA108, LA110, LA112, and LA127/140, were identified. Representative isolates of each were pathogenic on cotton in greenhouse assays. A unique genotype of FOV, MDS-12, which was characterized with additional sequencing of the phosphate permease-like protein, β-tubulin, and intergenic spacer regions, was identified in Alabama, Arkansas, Mississippi, Louisiana, and Georgia. FOV race 4 was not detected outside of California.