According to the United States Census Bureau, the city has a total area of 1.1 square miles (2.7 km2), all land.

In 1921, still a tiny community based around the ranching industry, it was designated the county seat.

Rankin was served by the Kansas City, Mexico and Orient Railway.

The discovery of the Yates Oil Field in adjacent Pecos County in 1926 converted Rankin into a boom town.

Since Rankin was the nearest settlement on a rail line, it became the center for the oil-services industry for the nearby oil fields.

During the Great Depression, the population declined as the price of oil fell, and as workers moved away to work in newly discovered fields in East Texas and elsewhere; however, a secondary boom occurred in the 1940s with the discovery of the nearby Benedum Oil Field.

As of the 2020 United States census, 780 people, 352 households, and 245 families were residing in the city.

[11] Rankin experiences a semiarid climate with hot summers and cool winters.