(1) United States Postal Service (USPS): USPS is a postal service of the United States government responsible for handling mail and parcels within the United States and internationally. USPS provides different international express delivery services, including priority mail international service and express mail international service.

(2) Express companies: In addition to USPS, there are many other express companies that can provide delivery services for small packages in the United States, such as FedEx, DHL, and UPS.