As part of my research for my Western novel, which employs dialect speech rather than the "Queen's English", I did a lot of research into mid-19th century accents, dialects and so on. It was very interesting. I found YouTube very helpful, with many videos dealing with different American accents and patterns of speech. I thought you might be interested in a few of them.
To start with, why do pre-World-War-II movie actors sound odd to modern ears?
Next, the famous Appalachian 'hill country' speech - what is it and where did it come from?
Finally, how many dialects or versions of English are there in the USA? One professor says there are no less than 15 - but the language is changing fast.
I don't know about you, but I find the subject very interesting. I hope you enjoyed the videos.