In previous work, I have documented and analyzed the persistence of mainstream ideologies around 'standard' and 'nonstandard' American English in the adult ESOL classroom and their connection to linguistic racism and anti-Blackness. This study explores how these ideologies developed more broadly, employing elements of raciolinguistic genealogy and metapragmatics to analyze historical language scholarship. I find that while the linguistic features of ‘nonstandard’ English have remained remarkably consistent in the popular imagination, they became increasingly linked with Blackness, especially during and after white backlash to the Great Migration (and other cultural and political changes) in the mid-20th century. I argue that this represents a larger pattern in the relationship between language and race in the United States, and conclude with a discussion of the implications this has for adult immigrants and the ESOL classroom.