USA is on the list of countries entitled for tourist visa exemption. US passport holders may enter Thailand without a visa (tourism purpose only). Permitted period of stay is 30 days.
Yes, the tourist Visa is issued in Bangkok upon arrival and is good for thirty days. It may be renewed twice, I believe, within a six month period. You do not have to have a tourist visa for Thailand prior to departure from the US.
No you don’t need any visa
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