The efforts of the United States Postal Service often go unnoticed. Though many professionals can stay home during adverse weather events like blizzards, postal workers report to work every day. Those heroic efforts have been on full display during the pandemic, when postal workers continued to report to work and deliver the mail at a time when public health officials urged citizens to stay home as much as possible.

July 1 is National Postal Worker Day in the United States, making it an ideal time to honor the efforts of these dedicated professionals. One way to honor postal workers is to learn about the centuries-old history of the USPS. The following are some significant events in the history of an institution that plays such a vital role in the daily lives of hundreds of millions of Americans.

• The U.S. postal system was established by the Second Continental Congress on July 26, 1775. Founding father Benjamin Franklin was named the first postmaster general. Franklin had been one of two postmasters general for the colonies, but was fired by the British in 1774 for his revolutionary efforts.

• The first general issue postage stamps went on sale in New York City on July 1, 1847. Among the notable figures to appear on the stamps are Franklin and the first president of the United States George Washington.

• The Pony Express system of delivering U.S. mail began in 1860. The service employed relays of horse-mounted riders who delivered mail between Missouri and California. Though the service proved vital in connecting California with the rest of the United States, it was not destined to do so for very long, as it went bankrupt in just 18 months.

• Scheduled airmail service began in 1918, but the first authorized U.S. mail flight occurred years earlier. Aviator Earle Ovington piloted the first such flight on September 23, 1911. Mailbags from the planes of Ovington and seven other pilots were dropped from the plane to the ground, where they were picked up by the Postmaster of Mineola, New York, William McCarthy.

• The USPS introduced ZIP codes in 1963. The very first ZIP code was not granted to any place in mainland United States, but rather to Adjuntas in Puerto Rico. It would be another 20 years before the USPS would adopt the ZIP+4® Code, a system it still utilizes today.

• The USPS launched its public internet site in 1994. That means the USPS website was available prior to many other notable online entities, including Amazon, which did not officially open for business as an online bookseller until July 16, 1995