We tend to think of innovators in the public sector as those agencies working together with flashy startups to get the next big idea in government, and the United States Postal Service usually isn’t part of that group. But that wasn’t always the case.

A story by Kevin Kosar explores the idea that throughout much of its history, the title of the most innovative agency in government could have easily been handed to the Post Office, as it was officially called until 1970. To figure out how to deliver mail across the country quickly and cheaply, the postal service had to think big.

For example, in 1897, work began on a system of pneumatic tubes beneath the streets of Philadelphia to shoot letters around the city in just a few minutes, and it was funded through a public-private partnership between the city and the Pneumatic Transit Company of New Jersey. In 1959, the agency proposed sending mail across the country via guided missile. While the plan didn’t pan out, it certainly would have been groundbreaking.

For generations, U.S.P.S. “integrated new technologies and adapted to changing environments, underpinning its ability to deliver billions of pieces of mail each year,” Kosar wrote on Politico, “from the beaches of Miami to the banks of Alaska, for just cents per letter.”