Postcards are frequently classified by the era in which they were produced. The following descriptions of five eras refer to cards made in, or especially for, the United States market. There are also some earlier and less common "pioneer" era postcards.

Early Twentieth Century

The Golden Age of postcards lasted from the beginning of the century until 1918. Before World War I, most of the better quality cards were printed in Europe. Postcards were very popular as collectibles, and many were saved. Printing was usually high quality, though many of the comics are cheap looking. Greeting cards are colorful and usually embossed. View cards usually have good detail, deep colors, and no border. Real photo cards printed on photo paper were made in limited quantities on a wide variety of local subjects. Studio portraits and family snapshots were also often printed as postcards.

White Border

This type was produced mainly from 1919 to 1932. View cards usually have white borders and low-contrast pale colors. The printing is usually not as good as that on earlier cards. Paper stock is usually coated and has a flat non-glossy surface. Most of the cards from this era are views. Greeting cards were uncommon, unembossed, and less colorful.

Linen

From 1933 until the early 1950's most U.S. views and comics were printed on card stock with a linen texture. Advertising, large-letter, expositions, and comics from this era are generally attractive and collectible. The majority of view cards from this era are boring and unattractive, especially those featuring scenery. Real photos of tourist areas were also fairly common in this era. The real photos cards from this era are generally glossier and more contrasty than earlier ones and have titles in white letters near the bottom of the picture.

Standard/Chrome

Chrome cards have a glossy surface and are made from color photos. This type of postcard was produced as early as 1939, but was not common until the mid-1950's. Until the mid-1970's most U.S. cards were the "standard" size, approximately 3-1/2 X 5-1/2 inches.

Continental/Modern

"Continental" size is approximately 4 X 6 inches. This size was common in Europe earlier than in the U.S. Most of the cards sold in the U.S. since the mid-1970's are this size. View cards are relatively fewer and more generic than in earlier eras. A large variety of subjects have been produced on modern cards aimed at collectors. These include both individual cards and many books of removable postcards. Holiday greeting postcards are available but not very common.

Super-sized postcards approximately 5" X 7" have been appearing more recently. These are smaller than most of the over-sized cards of the past, but are too large to mail at the regular postcard rate (maximum size: 6 inches long by 4-1/4 inches high).