There aren’t quite as many American accents as those in Britain. However, they vary quite a lot from the east coast to the west, despite the prevalence of General American all over the country.
Here’s a map that focuses on most of the varieties.
In case you want to download it in high resolution.
Field Practice
Now, check out these videos and identify the accents. Keep in mind that none of the speakers will exhibit all the characteristics of a particular accent. Also, you aren’t expected to comprehend every single word they utter.