Portales is located near the larger city of Clovis, and Cannon Air Force Base, a major contributor to the economy of the region.

It is the principal city of the Portales micropolitan statistical area, which is part of the larger Clovis-Portales combined statistical area, including Clovis, 19 miles (31 km) away and Cannon Air Force Base, 13 miles (21 km) away.

The US territorial settlement of Portales occurred in the late 19th century as cattle herders discovered a water source emanating from a rocky ledge resembling a Spanish porch.

[6][7] In particular, given its access to the Ogallala Aquifer, improved surface irrigation techniques supported steady growth in agriculture.

In 2023, the FW1 Ute Reservoir pipeline project started construction to provide potable water by 2030 for Cannon Air Force Base and the communities of Clovis, Portales, Elida, Texico.

According to the United States Census Bureau, the city has a total area of 6.8 square miles (18 km2), all land.

The city's downtown area is centered around a traditional-style town square, based upon Spanish urban design.

Eastern New Mexico University (ENMU) forms a sizable district with its campus and surrounding residential stock catering largely to students.

Portales has a semiarid climate (Köppen climate classification BSk) with hot summers featuring most of the year's rainfall from thunderstorms during the latter half of the season, plus dry winters with typically freezing mornings and mild, sunny afternoons.

By 2007, per capita income had risen significantly, while the poverty rate had dropped, in large part due to massive growth in the dairy industry.

[16] The Portales economy is also connected to Cannon Air Force Base located about 13 miles (21 km) to the north.