When people think of wildlife trade, they often picture smugglers sneaking in rare and endangered species from far-off countries. Yet most wildlife trade is actually legal, and the United States is one of the world's biggest wildlife importers. New research that we and a team of colleagues published in the Proceedings of the National Academy of Sciences shows that, over the last 22 years, people in the U.S. legally imported nearly 2.85 billion individual animals representing almost 30,000 species. Some of these wild animals become pets, such as reptiles, spiders, clownfish, chimpanzees and even tigers. Thousands end up in zoos and aquariums, where many species on display come directly from the wild. Medical research uses macaque monkeys and imports up to 39,000 of them every year. The fashion trade imports around 1 million to 2 million crocodile skins every year. Hunting trophies are also included in wildlife. The largest number of imported species are birds - 4,985 different species are imported each year, led by Muscovy ducks, with over 6 million imported. Reptiles are next, with 3,048 species, led by iguanas and royal pythons. These largely become pets. We found that just over half of the animals imported into the U.S. come from the wild. Capturing wildlife to sell to exporters can be an important income source for rural communities around the world, especially in Africa. However, wild imported species can also spread diseases or parasites or become invasive. In fact, these risks are so worrying that many imported animals are classed as "injurious wildlife" due to their potential role in transmitting diseases to native species.