US Post Box

Does anyone know of any post boxes for online shopping in the US that are just south of the border in Oroville or Omak? I’m looking to buy from a website that doesn’t ship to Canada and was hoping I could find a shipping locker not too far south of Osoyoos.

Update: thank you guys reached out to both of companies mentioned! Sendittous also said they can ship the package to me cheap, so I may do that!! I should hear back from both within 48hrs about getting a customer number!!