What mammal order includes elephants?

The mammal order that includes elephants is Proboscidea.

Proboscidea contains the elephant family, Elephantidae, along with extinct relatives such as mammoths, mastodons, gomphotheres, and deinotheres. The order was named by Johann Karl Wilhelm Illiger in 1811, and its name refers to the distinctive trunk, or proboscis, found in many of its members.

The earliest proboscideans appeared in Africa about 60 million years ago and were far smaller than modern elephants. Over time, some lineages evolved immense bodies, tusks, specialized molars, and elongated trunks. Three living elephant species remain: the African bush elephant, African forest elephant, and Asian elephant.

A common mix-up is confusing an order with a family. Elephants belong to the family Elephantidae, but Elephantidae is only one family within the broader order Proboscidea. Their closest living relatives are not rhinoceroses or hippopotamuses, but hyraxes and sirenians such as manatees and dugongs.