By 1908 El Fuerte was large enough to warrant a school. A two room adobe building was erected on land just east of this site. There was also a teacher's cottage and a small stable, where the children left their horses and burros. About 50 pupils enrolled, grades one through four in one room, five through eight in the other. In addition to those living in El Fuerte, children came from ranches and farms as far away as Sabino Canyon. Teachers were paid $100 a month and earned extra money by transporting students. By 1926 the school needed more space, so two classes moved over to this church building and two more teachers were hired. By 1929, there were nearly 100 children in the school, so the district built a new Fort Lowell School one and 1/2 miles away on East Pima. The children carried all the desks and books across the desert to the new school. The original school building and teacherage were then used variously as a dance hall and bar, a chicken farm, and now as a private residence.
The Old Fort Lowell Union Church was built of mud adobe in 1913, making it the oldest religious structure in El Fuerte. The long rectangular building still contains the original wooden floor, with a stage at the north end. Heat was provided by a wood stove. During the school week, a folding door divided the room. On Sundays the desks were pushed aside and church services held. The children planted a garden to the east of the church and soon the teachers and mothers began fixing hot lunches in the teacherage - the first hot lunch program in Pima County. This evolved into the Fort Lowell Homemakers Club, which met in the Union Church until 1945.
In the 1940's, an extension was added on the west side, but the church building remained unplastered until 1953. Until 1963 the Old Fort Lowell Union Church was home to a number of congregations. Since then, the Pan-American Literature Mission has used the old church for its international mail ministry.