[3] The American white pelican was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

Latham had access to three specimens that had been brought to London from New York and the Hudson Bay area of North America.

[8] The American white pelican rivals the trumpeter swan, with a similar overall length, as one of the longest birds native to North America.

After moulting into the eclipse plumage, the upper head often has a grey hue, as blackish feathers grow between the small wispy white crest.

[3] The bill is huge and flat on the top, with a large throat sac below, and, in the breeding season, is vivid orange in color as is the bare skin around the eye and the feet.

Outside the breeding season, the bare parts become duller in color, with the naked facial skin yellow and the bill, pouch, and feet a dull pink-orange.

[3] American white pelicans nest in colonies of several hundred pairs on islands in remote brackish and freshwater lakes of inland North America.

[14][15] They winter on the Pacific and Gulf of Mexico coasts from central California and Florida south to Costa Rica, and along the Mississippi River at least as far north as St. Paul, Minnesota.

In Colombian territory, it was recorded first on February 22, 1997, on the San Andrés Island, where they might have been swept by Hurricane Marco which passed nearby in November 1996.

[18] Typical fish prey include Cypriniformes like common carp (Cyprinus carpio), Lahontan tui chub (Gila bicolor obesa),[19] minnows,[20] and shiners.

[24] Birds nesting on saline lakes, where food is scarce, will travel great distances to better feeding grounds.

The nest is a shallow depression scraped in the ground, into which some twigs, sticks, reeds, or similar debris have been gathered.

After fledging, the parents care for their offspring some three more weeks, until the close family bond separates in late summer or early fall, and the birds gather in larger groups on rich feeding grounds in preparation for the migration to the winter quarters.

[3] Occasionally, these pelicans may nest in colonies on isolated islands, which is believed to significantly reduce the likelihood of mammalian predation.

Human-related losses include entanglement in fishing gear, boating disturbance, and poaching as well as additional habitat degradation.

[29] There was a pronounced decline in American white pelican numbers in the mid-20th century, attributable to the excessive spraying of DDT, endrin, and other organochlorides in agriculture as well as widespread draining and pollution of wetlands.