The Lights That Kept the Mail Moving

An airplane could carry letters faster than a train, but early mail planes had a problem: darkness. Pilots depended on seeing the ground to find their way. For a time, sunset interrupted the mail's trip by air. The dated headings below trace how lights helped turn separate daytime flights into a service that continued through the night.

1918–1920: Flying by Day Regular United States airmail service began in May 1918 between Washington, D.C., Philadelphia, and New York City. In September 1920, a coast-to-coast route connected New York and San Francisco. A route is a path between places. However, this did not mean that each letter traveled the whole distance by airplane. Planes carried mail during daylight. At night, workers transferred mailbags to trains. The bags could return to airplanes when daylight came. Switching between trains and planes kept letters moving, but it also took time.

1921: Testing the Darkness In February 1921, a special coast-to-coast test helped show that mail could travel by air after sunset. Pilot Jack Knight flew a nighttime section from North Platte, Nebraska, through Omaha to Chicago. People on the ground used fires to help mark landing places. The test showed what night flying might make possible. Still, a few fires were not a dependable guide for regular service. Pilots needed signals they could count on, both along the route and at landing fields.

1923: Building a Trail of Lights During 1923, the Post Office tested a lighted airway between Cheyenne, Wyoming, and Chicago, Illinois. An airway was a route for aircraft to follow. Along it, towers held powerful signal lights. Each beacon sent out light that pilots could spot from the air. Some lights had rotating beams that swept around like a lighthouse beam. Lights also marked landing fields. Instead of relying on a few fires during a special test, pilots now had a planned chain of signals to follow.

1924: Keeping the Mail in the Air On July 1, 1924, scheduled coast-to-coast airmail service began using nighttime flights. Scheduled service followed a regular timetable rather than operating as a single test. The lighted section helped planes carry mail through the middle of the country after dark. Workers no longer had to put those mailbags on trains simply because night had arrived. Letters could cross the country sooner.

The change took several years, not one flight. Daytime routes came first, followed by a night test, a lighted airway, and regular overnight service. Mail delivery worked like a relay, with pilots and ground workers taking turns. A chain of lights helped keep that relay moving after sunset.