Dos Lomitas Ranch, Historic ranch district in Organ Pipe Cactus National Monument, Arizona, US.

Dos Lomitas Ranch is a historic ranch property near the US-Mexico border within Organ Pipe Cactus National Monument. The buildings feature adobe brick construction with thick walls, wooden beam ceilings, and corrugated metal roofing, while packed earth composed the original flooring.

Dos Lomitas Ranch was the first of fifteen ranches and line camps in the Gray family cattle business. The period of significance begins with the purchase of the ranch's water rights in 1919 and ends with the death of Robert Gray Jr., the last of the three Gray sons, in 1976, followed by the removal of the family's last cattle from Organ Pipe Cactus National Monument.

The structures display building methods adapted to desert living, with thick adobe walls and wooden beams that reflect how people constructed durable homes in an arid landscape. Visitors can see how local materials were chosen and arranged to withstand extreme heat and maintain cool interiors.

The ranch lies within Organ Pipe Cactus National Monument, reached by driving the monument's roads north of the US-Mexico border in Arizona. The main house and the railroad-tie outbuilding stand close together, so the site can be walked in a short time. Desert heat is severe; carry water and wear sturdy shoes for packed earth and gravel.

The property retains its original packed earth flooring in several rooms, today offering a rare glimpse into early 1900s living methods. This flooring choice was practical for the time, helping to keep interiors cool during the hottest months.