On June 8, 1959, a large Regulus I nuclear missile pointed straight at America’s shoreline. The missile was perched on a submarine lurking about 100 miles off the Florida coast. Just before noon, it blasted into the clouds, traveling more than 100 miles in just 22 minutes, and landed squarely on its target, the Naval Auxiliary Air Station in Jacksonville, Fla.—successfully delivering 3000 pieces of mail.

For as long as people have been sealing envelopes, they’ve been finding ways to get messages to their destination faster. During the late 1800s, mail balloons and gliders competed with carrier pigeons for airspace. When airplanes swooped in, people were still unsatisfied with the wait. By the 1930s, inventors were toying with something even faster: rockets.

The idea wasn’t new. Scientists had been mulling “mortar mail” since 1810, with mixed results. In the 19th century, people on the island of Tonga used military rockets to blast mail over the reefs to Samoa. (Most crashed into the sea.) After World War I, German and Austrian scientists resurrected the idea. In 1931, an amateur rocketeer named Friedrich Schmiedl successfully launched 102 letters across a mountain in the Alps. Shortly after, businessman Gerhard Zucker pitched the idea to the U.K. government. He exhibited the technology by stuffing more than 1,200 envelopes into two rockets and firing them over some Scottish isles. They exploded.

The United States didn’t take rocket mail seriously until the Cold War. By then, the volume of mail had spiked more than 30 percent and Arthur Summerfield, the postmaster general, was desperate to deal with the glut. So in 1959, officials hosted an experiment: They transformed the USS Barbero, a nuclear sub, into a floating post office. They removed the nuclear warhead on a Regulus I cruise missile, replaced it with two postal mail containers, and blasted it to Florida. It stuck a perfect landing.

Summerfield joyfully declared, “Before man reaches the moon, mail will be delivered within hours from New York to California, to Britain, to India, or Australia by guided missiles. We stand on the threshold of rocket mail.” He neglected the fact that postal workers needed time to sort and route the mail. Plus, it was the 1950s. Americans weren’t super excited to see rockets zooming over their backyards. The government eventually got the memo.