Which postal service is responsible for the delivery of standard mail?

The United States Postal Service (USPS) is the organization specifically designated to handle the delivery of standard mail within the United States. It operates under the authority of the federal government and provides essential postal services to the public. USPS is responsible not only for the delivery of letters and packages but also for a variety of mail services, including first-class mail, marketing mail, and periodicals.

While other companies, such as FedEx, UPS, and DHL, provide package delivery services, they primarily focus on expedited shipping and do not handle standard mail delivery in the same capacity as USPS. These private carriers are known for their speed and reliability in parcel delivery but are not authorized or structured to manage the broad spectrum of standard mail services that USPS provides. Thus, the specific role of USPS in the postal system makes it the correct choice in this context.