The first American postcard was developed in 1873 by the Morgan Envelope Factory of Springfield, Massachusetts. These first postcards depicted the Interstate Industrial Exposition that took place in Chicago. Later in 1873, Post Master John Creswell introduced the first pre-stamped "Postal Cards", often called "penny postcards". Postcards were made because people were looking for an easier way to send quick notes. Postcards, in the form of government postal cards and privately printed souvenir cards, became very popular as a result of the Columbian Exposition, held in Chicago in 1893, after postcards featuring buildings were distributed at the fair.

The Post Office was the only establishment allowed to print postcards, and it held its monopoly until May 19, 1898, when Congress passed the Private Mailing Card Act, which allowed private publishers and printers to produce postcards. Initially, the United States government prohibited private companies from calling their cards "postcards", so they were known as "souvenir cards". These cards had to be labeled "Private Mailing Cards". This prohibition was rescinded on December 24, 1901, from when private companies could use the word "postcard". From March 1, 1907 the Post Office allowed private citizens to write on the address side of a postcard. It was on this date that postcards were allowed to have a "divided back".

On these cards the back is divided into two sections: the left section is used for the message and the right for the address. Thus began the Golden Age of American postcards, which peaked in 1910 with the introduction of tariffs on German-printed postcards, and ended by 1915, when World War I ultimately disrupted the printing and import of the fine German-printed cards. The postcard craze between 1907 and 1910 was particularly popular among rural and small-town women in Northern U.S. states. In 1908, more than 677 million postcards were mailed.

Another type of postcard that began to be produced and popularly used during the Divided Back period is the “real photo” postcard. “Real photo” postcards were first produced using the Kodak “postcard camera.” The postcard camera could take a picture and then print a postcard-size negative of the picture, complete with a divided back and place for postage.

With the beginning of World War I, American printers supplied most of the postcards in the United States. American printers did not have the same technology as German printers, so the quality of available postcards fell, and people lost interest in collecting them, effectively ending the “Golden Age” of postcards. Printers saved ink during this time by not printing to the edge of the card and leaving a white border around the image, giving the time period its name. Postcards from the White Border Period also had a description of the image on the message side, which retained the divided back. The White Border Period lasted from about 1916 to 1930.

Mid-century linen postcards were produced in great quantity from 1931 to 1959. Despite the name, linen postcards were not produced on a linen fabric, but used newer printing processes that used an inexpensive card stock with a high rag content, and were then finished with a pattern which resembled linen. The face of the cards is distinguished by a textured cloth appearance which makes them easily recognizable. The reverse of the card is smooth, like earlier postcards. The rag content in the card stock allowed a much more colorful and vibrant image to be printed than the earlier "white border" style. Due to the inexpensive production and bright realistic images they became popular.

The last and current postcard era, which began about 1939, is the "chrome" era, however these types of cards did not begin to dominate until about 1950. The images on these cards are generally based on colored photographs, and are readily identified by the glossy appearance given by the paper's coating.

Sources:

Smithsonian Institutional Archives. Postcard History.

https://siarchives.si.edu/history/featured-topics/postcard/postcard-history Accessed 2018-10-21.

Wikipedia. Postcard. https://en.wikipedia.org/wiki/Postcard Accessed 2018-10-21.