I am going to be traveling to Nigeria and I was told that the beef jerky there is excellent. I want to bring some back home to the US after my trip. Is it legal to do so through the US customs?
It sounds like you are referring to kilishi, which is very thin strips of meat spiced and sun-dried.
If it were from another country, the answer would be maybe. Commercially packaged shelf-stable beef products are sometimes admissible. However, there are exceptions:
It will be very difficult to bring any sort of meat from Nigeria into the US because of the incidence of foot and mouth disease in that country. The US does not allow import of meats from countries having issues with foot and mouth disease or mad cow disease (BSE) at all.
As a general rule - if goods are cooked and in shelf-stable (does not require refrigeration) packaging such as cans or other hermetically sealed containers AND they are not from a country affected with various diseases such as Avian influenza, Mad Cow disease, Swine Fever, Exotic Newcastle Disease, etc., they may be admissible.
In any event, if you are bringing food into the US you must declare it.
If you are looking for something similar, try biltong. It is usually sliced thicker than kilishi, though. And you can make either at home; many recipes can be found online for both kilishi and biltong.
CBP tends to confiscate meat products.
You might find this site helpful.