The branch did all its contracting through the Service's procurement officer, Roger Rittase. An artist himself, Rittase appreciated the difficulty of writing bid specifications for exhibit production. Display firms did most of their business for clients who wanted to sell something, while museum exhibits had a quite different psychological purpose and operated in a less strident environment. The different aesthetic quality and effect desired proved baffling to describe in unmistakable terms. Consequently the branch developed a bidding procedure that used the normal exhibit plan as the basic specification. Potential bidders studied the plan and in conference with the laboratory discussed in detail matters of style and practice required by museum standards. This was the situation when Mission 66 considerably augmented the exhibit production let to contractors.

When Rittase retired in November 1960, his replacement from the field, Houston Turner, took strong exception to the branch's procedure in exhibit contracting. His objection verged on a charge of unethical practice. While rejecting the implication, Assistant Director Price proposed that the new chief of property management select a procurement specialist whom the branch would hire to oversee contract purchasing at first hand. A procurement and property management officer for the branch accordingly entered on duty in August 1963. He did not solve the problem of writing tight specifications but introduced more formal bid conference procedures to ensure that each bidder perceived he had equal consideration.

A mid-course analysis indicated that during the first four years of Mission 66 the laboratories provided well over a thousand exhibits. These included ones for 37 visitor centers, close to the projected rate of ten new centers a year. The centers averaged only 23 exhibits apiece (counting information displays for the lobby as well as interpretive units for the museum), allaying fears of runaway development in park museums. Unit costs of preparing exhibits increased, but only moderately. The average per exhibit stayed between $1,300 and $1,400 through 1960. After 1961, with labor and material costs continually rising, the figure climbed above $1,800. Throughout Mission 66 both eastern and western laboratories strained for maximum output to keep pace with building construction schedules. Some new centers did have to wait for their exhibits, and in a few cases the laboratories had to store finished exhibits until a building was ready. Neither laboratory lowered its quality standards to speed the work. Both found satisfaction in the results.

The two laboratories, 2,800 miles apart, had very little opportunity to see each others' work. Each had its own talented designers and preparators. They worked on projects for different parks, each of which presented unique aspects for interpretation. Every visitor center was tailored to fit a specific situation. Most Mission 66 exhibits nevertheless shared a stylistic mode that Park Service people in particular noticed.