When I used to travel to the USA quite a lot for work (and used extra days to shop for #vinylrecords) I found that Portland, Oregan was one of the best places (with a well organised shops - map with specialisms of the shops) for picking up great records.....
Portland is an excellent vinyl-shopping town. I visited a couple years ago and really enjoyed it. Barclelona might be my favorite vinyl-shopping town, I overdid it on a visit there a few years ago. Wah Wah Records is tremendous.