Photo taken of a Prong Horn Antelope grazing at Antelope Island, Utah.

Adult males are 1.3–1.5 m (4 1/4-5 ft) long from nose to tail and stand 81–104 cm (2 5/8-3 3/8 ft) high at the shoulder, and weigh 40–60 kg (88-132 lb). The females are as long, but average slightly less heavy, 40–50 kg (88-110 lb). The main color of adults is brown or tan, with a white rump and belly and two white stripes on the throat. A short dark mane grows along the neck, and males also sport a black mask and black patches on the sides of the neck. The tail is short, 7.5–17.8 cm (average 13.5 cm) long. The feet have just two hooves, with no dewclaws. The body temperature is 38.0 °C.

Each “horn” of the pronghorn is composed of a slender, laterally flattened blade of bone that grows from the frontal bones of the skull, forming a permanent core. As in the Giraffidae, skin covers the bony cores, but in the pronghorn it develops into a keratinous sheath which is shed and regrown on an annual basis. Unlike the horns of the family Bovidae, the horn sheaths of the pronghorn are branched, each sheath possessing a forward pointing tine (hence the name pronghorn). The horns of males are well developed; in females, they are either small, misshapen, or absent.

Males have a prominent pair of horns on the top of the head, which are made up of an outer sheath of hairlike substance that grows around a bony core; the outer sheath is shed annually. Males have a horn sheath about 12.5–43 cm (mean 25 cm) long with a prong. Females have smaller horns, ranging from 2.5–15 cm (average 12 cm), and sometimes barely visible; they are straight and very rarely pronged. Males are further differentiated from females in that males will have a small patch of black hair at the corner of the jawbone. Pronghorns have a distinct, musky odor. Males mark territory with a scent gland located on the sides of the head.They also have very large eyes, with a 320 degree field of vision. Unlike deer, pronghorns possess a gallbladder.

It can run exceptionally fast, being built for maximum predator evasion through running, and is generally accepted to be the fastest land mammal in the New World. The top speed is very hard to measure accurately and varies between individuals; it is variously cited as up to 70 km/h, 72 km/h, or 86 km/h. It is often cited as the second-fastest land animal, second only to the cheetah.] It can however sustain high speeds longer than cheetahs. The pronghorn probably[citation needed] evolved its running ability to escape from the recently extinct American cheetah, since its speed greatly exceeds that of extant North American predators. It has a very large heart and lungs, and their hair is hollow. Although built for speed, it is a very poor jumper. Their ranges are often affected by sheep ranchers’ fences. However, they can be seen going under fences, sometimes at high speed. For this reason the Arizona Antelope Foundation and others are in the process of removing the bottom barbed wire from the fences, and/or installing a barbless bottom wire.

Gaits used by the pronghorn include the highly distinctive pronk, a leaping gait.

Photo taken by Canon IXUS