I wonder about silly stuff like that, too, and when I first saw a green card that wasn't green, I decided to find out why. Prior to the passage of the Internal Security Act in 1950, there were several different kinds of cards that aliens could have, depending on their status. In 1940 current aliens had to register at the Post Office, and after WW II that was changed to be a part of the normal immigration process at ports of entry. A current alien received an AR-3 Alien Registration Receipt Card, which merely meant they were registered, but had no determination of legal or illegal status. Other Receipt Cards were issued to visitors, temporary foreign workers, students, etc. All of these Receipts Cards had different numbers and different titles, and they were all different colors. And it was confusing to aliens, immigration attorneys, employers, immigration officials, everybody.
With the 1950 Internal Security Act, the "Golden Ticket" of immigration Receipt Cards became the Alien Registration Receipt Card for Lawful Permanent Residents Form I-151, and was green in color. Just as I-151's were only issued to Lawful Permanent Residents entering through ports, only aliens with legal status could have their old AR-3 replaced with an I-151. Unlike today, employers in the 1950's would not hire an alien without a I-151, so being able to convert your AR-3 into the I-151 card of a Lawful Permanent Resident was a big deal.
Because of the confusion and the length of the card titles, and many new immigrants still struggling with English where the formal titles of the various cards was a nightmare to comprehend, everyone, including immigration officials, began referring to the Alien Registration Receipt Card for Lawful Permanent Residents Form I-151 simply as the "green card."
The term "green card" designated not only the document itself, but also the official status desired by so many legal non-immigrants (students, tourists, temporary workers) and undocumented (illegal) aliens. The status became so desirable that counterfeit Form I-151's became a problem.
To combat document fraud, the INS issued 19 different designs of the I-151 between its introduction in the 1940's and its complete revision in 1977. One alteration to the design in the 60's was to change the color of the card to a pale blue, and then a year later change it to a dark blue. Regardless of color, the I-151 still carried with it the benefits indicated by the term "green card," and those who wanted, obtained, issued, or inspected I-151's continued to refer to it by that name.
The changes made in 1977 include machine readability, and the form number has changed a few times to its current I-551 ('cause leaving it at I-151 would make too much sense). It's been issued in a rainbow of colors, including multicolors like pink and blue. For a short time it was officially a "salmon" color, until someone stepped in who likely feared seeing future cards being issued in a plethora of LL Bean Catalog colors like sea foam, sand, auburn, mauve and heather.
Green cards, pink slips and yellow journalism, they've all got their storied and colorful histories. But at least the Green Card is one you can now file away in your junk drawer of useless trivia.
