There are two ways to do this...
First, you can open a USD account at an Arg bank, deposit some dollars, and then do an international wire from your Arg USD account to the US Bank recipient. This obviously has some complications. You need to buy dollars from a source and the bank will obviously inquire how you earned them. It will also cost around $90 in international wires fees split between the sender and the recipient.
Second, you can visit Saldo.com.ar to do the above using virtual dollars. Saldo is a peer-to-peer platform that works with dozens of apps. I would recommend you use Paypal. Not all apps listed connect to a USD account. Paypal is one that does. You will need to open a Paypal account and your recipient will need one too. You purchase Paypal dollars (using Saldo) with Arg pesos. You then transfer your Paypal dollars (using Paypal's website) to the recipient's Paypal account. The recipient then requests their Paypal dollars be transferred to the their USD account. Expect to pay platform commissions for your virtual dollar purchase. Be sure to use "family and friends" for your paypal transfer instead of "goods and services" to avoid paypal fees and a 1099 to the recipient.