Americus Callahan

Americus F. Callahan, of Chicago, Illinois, in the United States, received the first patent for a windowed envelope on 10 June 1902. Originally called the "outlook envelop", the patent initially anticipated using thin rice paper as the transparent material forming the window, though this material has since been replaced by clear plastics. The design has otherwise remained nearly unchanged. cite web|url=http://www.tecsoc.org/pubs/history/2002/jun10.htm |title=Today in Technology History: June 10 |accessdate=2007-06-05 |work=Center for the Study of Technology and Society |publisher=tecsoc.org]

The design and patent letter were completed on 15 November 1901, with the patent filing occurring on 9 December 1901. The United States patent number for Callahan's design is 701,839. cite web|url=http://www.google.com/patents?id=woxXAAAAEBAJ&dq=701,839 |title=US Patent 701,839 |accessdate=2007-06-05 |work=United States Patent and Trademark Office |publisher=google.com ]

The window permits text on the letter itself to be used simultaneously as the address of the recipient and the return-address of the sender, reducing the need to print the addresses onto the envelope itself. This amounts to a savings in materials, particularly through the reduction in ink usage; and also because the envelope can be substituted with lesser-quality paper as the envelope no longer must be written upon.

Callahan specifically recommended the use of Manila paper, which is considerably cheaper than thicker writing paper and also provides an opaque background for secure covering of the letter within. Callahan also recommends the use of black paper, which would likewise provide an opaque background whilst simultaneously increasing the contrast with the white address blocks.

Additional savings can be achieved by removing the time spent inscribing additional addresses upon the envelope. At the time, large business offices -- particularly within the telegram industry -- employed corps of envelope addressers who wrote the addresses upon envelopes. In addition to the labor costs, this method was prone to mismatches, where the address on the letter header within would not be the same as the address upon the envelope.

Owing to the benefits in both time, cost, and quality, the windowed envelope design has become nearly ubiquitous among modern commercial mailings. cite web|url=http://www.census.gov/pubinfo/www/radio/pa0610.htm |title=US Census Bureau: Profile America |accessdate=2007-06-05 |work=United States Census Bureau |publisher=Public Information Office]

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