By November the committee had settled on ten trails, abandoning a plan that would have created eleven. The driving routes had been mapped out with the assistance of highway engineers and would be marked with distinctive signage. They decided the Trail signs would be brown, to distinguish them from the Interstate system of green. They estimated some 1,500 signs would be needed, and an equal number of directional arrows. In January 1968 a memo and invoice went to each included county noting the breakdown of signs required, with a two-week deadline for payment.
By the time the committee actually ordered the signs a few weeks later, the choice had been modified to a medium blue and white, a distinctive scheme still recognizable fifty years later.
But it was no ordinary, run-of-the-mill shade. According to a newspaper travel feature in April 1968, when Frank Hildebrand apparently related the story to an enterprising reporter:
overnor Connally has had a strong hand in developing the new tourist program, even to designating the color of the signs marking the trails. The color choice had been narrowed to blue or green, cool colors that psychologists said would take tourists’ minds off the hot summer weather. When asked what color he would suggest, the governor, seated at his desk, pointed to a picture of his wife and said, ‘I would like to see it the color of Nellie's dress.’ And so the signs are ‘Nellie’s Blue.”G
The Southwell Company of San Antonio, makers of the signs, corroborates the unusual choice; in May W. P. Southwell, Jr., supplied Texas Highway Department district engineers with complimentary touch-up bottles of the “Nellie Blue” transparent paint, “slightly lighter in shade than your standard Interstate Blue,” that had been mixed especially for the project by 3M.