Regional Rate is a Priority Mail service with discounted rates.
It’s similar to Retail or Parcel Select Ground in that it costs more to send a package a longer distance. So sending from one zone to another costs more than sending within a zone.
It’s different from Retail and Parcel Select Ground because there’s a weight limit, and they charge the same regardless of weight.
Like Priority Mail Flat Rate, you need to use their boxes.
The 2018 prices are:
A – $7.10 to around $10 for most packages, 15 pound weight limit.
B – $7.41 to around $18 for most packages, 20 pound weight limit.
See Notice 123: Regional, PMOD, Cubic for the complete list of latest prices.
See USPS Regional Rate Box Sizes for a list of sizes and a link to the USPS store.
See Regional Rate Box vs. Flat Rate Box USPS for some ideas about how these boxes can help you save money.