You need transit visa to enter US. Check with your travel agent, unless you are Canadian citizen.
Don't really know I saw passports only but a safe bet would be carry your visa just in case , it's better to be prepared safe travels Saniya Samjhana
I don't think you will need a visa, just your passport. That said, I would check with the airline. You may have to go through customs.
If you are inside any airport, no visa is required. You are not entering into that country. It's just a transit.
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