The common gallinule is one of the most conspicuous rail species in North America, along with the American coot.

The gallinule has dark plumage apart from the white undertail, yellow legs and a red frontal shield.

Populations in areas where the waters freeze, such as southern Canada and the northern USA, will migrate to more temperate climes.

When threatened, the young may cling to a parent's body, after which the adult birds fly away to safety, carrying their offspring with them.

In addition to the extant subspecies listed below, there is a Pleistocene population known from fossils: the larger, stout and long-winged paleosubspecies G. g. brodkorbi is known from the Ichetucknee River deposits in Florida.

The presence in the same deposits of fossils typical of the shorter-winged and more delicate G. g. cerceris suggests that G. g. brodkorbi was not ancestral to the Antillean (Florida) gallinule of our time but rather to the more northerly North American subspecies.