Although the Post Office became the cornerstone of cross country flying, the military also made contributions. The transcontinental endurance race which took place in October of 1919 stands out as a statement of the possibilities and dangers of aviation. This test was the brainchild of the famous (or infamous) General Billy Mitchell, and consisted of 48 pilots attempting to fly from coast to coast and back again. Some started in New York and flew to San Francisco and some reversed the process. The race itself had military origins, but it became the first trial run for many airports west of Cleveland. Some of these existed because of the prior efforts of the Post Office.
The race did not follow the Post Office route precisely and it had additional stops, both for safety and to accommodate the fuel range of multiple types of aircraft. For example, while the Post Office flew through Bellefonte, Pennsylvania, the race flew through Birmingham, Rodchester, and Buffalo, New York. This route skirted the Appalachian Mountains, making it less hazardous. The route also stopped in Rock Island, IL and Des Moines, Iowa rather than Iowa City. This provided two evenly spaced stops between Chicago and Omaha instead of one. Despite the differences, many airports got their first chance to demonstrate their capabilities.
Omaha had not yet constructed a hangar, but seeded a landing strip, and maintained it by keeping brush and debris off the field. In preparation for the endurance race, the city removed wires or signs that could interfere with landing (Omaha Chamber of Commerce Journal). It also had supplies on hand such as gas, oil, and the occasional fresh spark plug. Cheyenne, Wyoming was located at the base of Sherman Summit, the highest crossing point along the way. In addition, it was the largest town in the area, the state capital, and along the railroad tracks pilots which guided pilots from coast to coast in an area with few rivers and other landmarks to guide them. The city of Cheyenne worked closely with the governor, which included borrowing graders from the state highway agency to prepare the field.
Although pilots had flown from coast to coast before, starting with Cal Rogers in 1911, it remained a difficult and hazardous undertaking. Navigational instruments and weather reporting did not exist in any reliable form. Although aviation activity increased following World War I, this cross country test would be the first time most of these fields had been used in such a widespread aviation feat.
The race was not a total success. Seven pilots died and it took vastly different amounts of time for them to cross the country, which led to negative publicity. But the race undeniably demonstrated the ability of pilots to travel cross country, and it demonstrated the devotion of individual towns to become part of this larger endeavor. The fields used were primitive. Many were level pieces of ground with limited services, but the feat of having an actual aerial road across the country was amazing. Many towns which would not host scheduled landings on the airmail route would regularly see pilots flying overhead and be available when those pilots had to make emergency landings. Towns like Sideny, Nebraska or Rawlings, Wyoming assisted more than one pilot due to weather or mechanical difficulty.
Military and Postal aviation are separate fields of study, but they do intersect. Many airports used during the military endurance race existed due to the efforts of the Post Office. And without the Postal Service seriously planning a cross country route, the race would have been much more difficult or impossible. But credit should be given to the military for first showcasing the logistical reality as well as the possibilities of an aerial road from coast to coast.