More information about who in the US has and hasn't merged those two sounds: https://en.wikipedia.org/wiki/Phonological_history_of_English_low_back_vowels#Cot.E

More information about who in the US has and hasn't merged those two sounds: https://en.wikipedia.org/wiki/Phonological_history_of_English_low_back_vowels#Cot.E2.80.93caught_merger https://en.wikipedia.org/wiki/Phonological_history_of_Englis... It's the cot-caught merger.