U.S. Bank (we) use the Automated Clearing House (ACH) secure network for external account transfers. To give you an idea on how the money is moved, here's a quick summary:

1. The customer (you) provides the transfer details, including the account and routing numbers.
2. We submit the request to the ACH.
3. The ACH sends the funds to the financial institution specified by the routing number provided.
4. The financial institution deposits the money using the account number provided.

The ACH network is the same one used by the Federal Reserve to clear checks between financial institutions. How the funds are sent is similar to how direct deposits and automated payments are made on loans and mortgages.