How Us customs works in connection flights? My flight is NY- Miami- Brazil, Brazil-Miami-NY.

How Us customs works in connection flights? My flight is NY- Miami- Brazil, Brazil-Miami-NY.?
I only have 1 hour between the connections, do i have to go trough US customs in Miami + New York when i come back? What if i don't make it at time because of the Customs? Would the Airline Company be responsible for getting me a new flight?
Air Travel - 2 Answers
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1 :
Unless the Department of Homeland Security has changed its rules, on your departure flight you would go through Customs in Brazil. On the arrival (returning) flight, normally you would go through customs in Miami. You should have your Customs Declaration form filled out before each flight - this willl save you time. If you missed a connecting flight because of having to change planes, they would be responsible for obtaining you another flight.
2 :
No. You only go through customs in Miami. I missed my flight because of a hold up at Customs in Miami, and the airline got me rebooked on another American Airlines flight, free of charge. Have a great trip!