The United States Postal Service delivers more mail to more addresses in a larger geographical area than any other post in the world. The Postal Service delivers to nearly 155 million addresses in every state, city and town in the country. Everyone living in the United States and its territories has access to postal products and services and pays the same for a First-Class postage stamp regardless of their location.USPS shipping for your business is easier and more convenient than ever everything is easier from rate calculation and pricing to tracking and proof of shipment.
This plugin offers shipping rates by USPS.
Please find more informartion about how to install plugins here.
The plugin is provided absolutely for free and includes source code. Find the project Github repository here.