A man named Isaac Laurin, originally from Martinique, established mining claims in the Campo Bonito and American Flag area in the late 1800s. He and several others created the Old Hat Mining District, and one of his claims was the American Flag mine and mill site. In 1877, he built the American Flag Ranch house, and when other miners came to the area the small community of American Flag was created.

In 1880, the community was large enough to have its own post office, and American Flag Ranch was designated for that role. The AFR Post Office remained open for 10 years, but by that time many of the mines had closed and most of the residents had moved on. The Post Office itself was decommissioned and closed in 1890. The American Flag Ranch House is believed to be the oldest Territorial Post Office building still standing in Arizona.

The American Flag Ranch then became a ranching headquarters and later a residence for many of the workers who migrated to the area. In the 1970s, owner Thelma Rowe donated the ranch house and barn to the Arizona Historical Society. The house was rented as a residence for many years, and eventually was designated a historic building on the National Register of Historic Places. In 1999, the Arizona Historical Society deeded the property to the Oracle Historical Society, and OHS immediately upgraded the electric, septic and water systems. Caretakers were installed, but it was difficult maintaining a continuous presence to monitor the property.

In 2011, the OHS Board of Directors met at the property to assess the situation, create plans and set goals for preserving the building and surrounds. The Board initiated a multi-year plan to restore and rehabilitate the property, and find a long-term caretaker to live on site and provide security. Board member Kevin Armbrust spearheaded this substantial and challenging restoration/rehabilitation project, with significant assistance from volunteers Brian Kirkpatrick, John Medley and Dan Piermarini.

After more than 4 years, the American Flag Ranch project was completed and a Grand Re-Opening celebration was held on September 26, 2015, including commemorative envelopes with “American Flag Ranch, Arizona” postmarks. The American Flag Ranch House is now a small museum with historic items and displays related to the area, including a post office, period furnishings, ranching and mining artifacts and photos. The American Flag Ranch is open by appointment by contacting OHS. Commemorative envelopes are also still available at the Acadia Ranch Museum and American Flag Ranch.