Interac e-Transfers are only available in Canada for individuals who have Interac-partnered bank accounts (most of them). So, no you cannot use Interac e-Transfer in the U.S. That being said, Interac does have a collaboration with Mastercard and Western Union to allow Canadians to send International Transfers.

When you're in the U.S. ready to pump gas at a pitstop or pick up some snacks at the drugstore, and you see a debit terminal at checkout, you may very likely be able to pay with Interac Debit. Cross Border payments allows you to securely use your debit card at approximately 2 million retailers in the U.S.