Zip code insignia is an inscription urging the use of ZIP Code, or depicting the "Mr. Zip" character.  In the early 1960s, the Post Office Department was seeking more efficient ways to process and deliver growing volumes of mail.  The Department developed a 5-digit number code for each address.  Enter Mr. ZIP®, a unique brand icon who used a letter and satchel to convince Americans to use ZIP Codes on their mail.  The use of the ZIP Code system began on July 1, 1963 and within a year of this character's introduction, between a third and a half of America was using a ZIP Code.  Zip Blocks appeared on the margins of many stamps between 1964 and 1994. 

Mr. Zip was based on an original design by Harold Wilcox, son of a letter carrier, for use by a New York bank in a bank-by-mail campaign.  Post Office Department artists retained the face but sharpened the limbs and torso and added a mail bag.  The new figure, dubbed Mr. Zip, was unveiled at a convention of postmasters in October, 1962.  Five different versions of the cartoon were used:

Cartoon of a waving Mr. ZIP and a "Use ZIP Code" slogan.

Cartoon of Mr. ZIP running and a "Use ZIP Code" slogan.

The registered Mr. Zip, with a registration (â) symbol and “USE CORRECT ZIP CODE” slogan.

Mr. ZIP's head appears together with "USE ZIP CODE" slogan. This is found only on the 1964 Nevada Statehood, Scott 1248, and the 5¢ Christmas issues, Scott 1254-57, 1276, and 1321.

The thin Mr. ZIP and "Use ZIP Code" slogan is found on only two issues: the 1946 Register and Vote, Scott 1249, and the Legend of Sleepy Hollow, Scott 1348.

  Mr. Zip Standing

  Mr. Zip Running

  Mr. Zip Registered

Mr. Zip's Head & "Use Zip Code" Slogan

  Thin Mr. Zip

Typically ZIP blocks are collected as blocks of four.  U.S. stamp blocks that include ZIP code messages are listed and valued in the Scott U.S. Specialized Catalog.  Mr. Zip was retired in 1986 but the Zip slogans continued to be used.

Various Zip Code slogans were used from 1964 through 1994, including “Use Zip Code”, “Use Zip Codes”, “It all depends on Zip Code”, and “Use Correct Zip Code”.  The slogans were registered beginning in 1978. 

"Use Zip Code" from a Booklet Tab 

"Use Zip Codes"

"Add Zip To Your Mail - Use Zip Numbers For ZipCode"

"Add Zip To Your Mail - Always Use Zip Code"