USPS is the United States Postal Services. You can post any package through them to any part of the world.
They can send virtually any item on your behalf, except a number of prohibited items, like processed woods, stocks, precious stones, perfumes, passports, paints, knives, ice, fruit juice, soft drink, credit card blanks, coins, collectibles, airline tickets and the likes.
They also do not help in shipping any jewelry that contains lead salt or precious stones.
Aside the above items, you can post any other package through them. They serve virtually all the towns in Nigeria. This means you can send any item through them to any of the 744 local governments in Nigeria.
Aside Nigeria, they also serve various other countries across the globe. They have developed partnership with FedEx Express and this enables them to cover all the countries covered by FedEx. You can send your documents as well as non-document items through them.
They do not give any additional surcharges for the services they offer you. The company accepts parcels all days of the week, including Saturdays and Sundays. Generally, it only takes about 5 days to deliver the parcel you send through them, including the ones you send on Saturdays and Sundays.
You can contact them through email directly on their website. Their website is at www.usps.com. You can link up with their customer service center at www.usps.com/help. They are however not open during public holidays. You will have to wait till the public holiday is over before sending or receiving mails through them.