The Museum/Visitor Center at Tumacácori National Park is an unusual structure.  Not only is it a fine example of Mission Revival architecture, but also it is constructed as an interpretive device so that visitors can better understand the architectural sense and history of this park's prime resource: the Tumacácori Mission complex.

Frank “Boss” Pinkley, the National Park Service head of the Southwestern monuments, had definite ideas about the utilitarian aspects of the museum building.  He wanted a low building that would not interfere with the historic mission complex and that was close to the parking lot so that visitors entered immediately.  He wanted a pleasing facade, but nothing too ornate.  He felt the building should be large enough for future expansion if required, but of a design that complemented the mission's architecture.  He wanted reproductions of doors, windows, and floor and ceiling structure that were found in other Sonoran missions of the Kino chain.  He also wanted a “view room” where visitors could look out at the mission complex, and he even set the axis of the museum building at a particular angle so that visitors could see that “knock-out” view he chose.

Pinkley sent a team of park service men to Sonora, Mexico, in October of 1935 to record the remaining mission structures of the Kino chain and to study the architectural elements.  The team had some difficulty with their task since there was an insurrection during which the presidente municipal and the chief of police of Santa Ana were murdered.  In addition, troops were rushed to Hermosillo, Nogales, Magdalena, Santa Ana and Altar.  All the churches had been closed and the furnishings removed the previous December by the Federal government.

Architect Scofield DeLong incorporated many of the elements he had seen in the Sonoran missions in his design for the museum building.  First, he chose construction materials similar to those used in the Sonoran missions.  Walls were of sun-dried adobe bricks and cornices of fired brick.

The enormous shell motif over the main entrance was patterned after the entrance to the mission church at Cocóspera.  The carved entrance doors, made by the Civilian Conservation Corps at Bandelier National Monument in New Mexico, were quite similar, although not exact duplicates, of those at San Ignacio.  Other paneled doors in the museum building were similar to the doors of Caborca.

The museum lobby, which houses the bookstore, has a corner fireplace and a floor of large bricks laid in a herringbone pattern. The ceiling beams are supported by carved corbels similar to the nave ceiling of Oquitoa.  The wooden grillwork on the office windows were copied from the choir loft at Tubutama.  The piers and arches of the museum portals were copied from those at Caborca.

The groin-vault ceiling and painted decorations of the View Room were chosen because they were frequently used in Sonoran missions - at San Xavier, Tubutama, and in the baptistry at San Ignacio.

Public works funds for the museum/visitor center were approved by the Secretary of the Interior in August of 1936 and in June of the following year the contract for the building was let.  Construction began two months later as a Works Progress Administration project.  The work was completed and accepted in December of 1937.  The official dedication took place April 23, 1939.  In 1987, fifty years after construction, the building was placed on the National Register of Historic Landmarks.

While the building phase was going on, exhibits for the museum were being carefully researched and assembled.  Highlights of the displays are three dioramas that show mission life, five statues of saints, and a model of the complete mission grounds.