In addition, there is the Private Mailing Card Era, Undivided Back Era, and the Divided Back Era. Postcard Eras begin with the Pioneer Era (1889 to 1898).
This period’s roots lie within the Columbian Exposition in Chicago.
That averages out to just more than nine postcards a year mailed for every person in the country.
With hundreds of millions of postcards mailed each year during the Golden Age of Postcards (1907-1915) it is not surprising that antique postcards are so popular and still readily available to collectors.
Those most prized by collectors are known as the “Gruss aus” cards. The cards usually reveal several views on the front with the words “Gruss aus.” This translates to “Greetings from.” It wasn’t long before the American and British markets produced their own domestic multi-view cards with the words “Greetings from” on them.
The back of American pioneer cards are not divided.
In identifying and dating postcards there are specific eras, defined by both style and dates; however, these dates do not account for the transition from one era to the next.