Guam

The flag dates from 1917. I have seen two versions of it, one with a palm tree (if it is a palm) growing from the yellow peninsula in lower part of the shield, and other growing from the white background cliffs. I think the first one is right (it seems to me more logical, but ...).

The ratio of it is 21:40.
Željko Heimer, 20 February 1996

Crampton's Flags and COA, 1985 notes the flag was adopted in 1917 and accepted by the Guam congress in 1948 with the red border added in 1960. Barraclough's Flags of the World, 1969 shows the Guam flag without the red border surrounding the shield. When was the red border added or is the information on the red border totally wrong (did it have the border from the beginning)?
Nazomi Kariyasu, 20 April 1998

The red stripe surrounding the shield represents the blood shed by its people. A description of the Great Seal of Guam can be found on the Guam government site. In fact there is even a color photograph of the site represented on the flag.

It will be interesting to now see what may happen to the flag as there is a movement to eliminate colonization in Guam. One of the primary leaders is the territorial governor. This coincides with the 100th anniversary of the U.S. acquisition of Guam. I remember a similar movement when I was stationed there in the early 1990's, however this movement was to upgrade the status to a Commonwealth.
Gene Duque, 20 April 1998

It would appear that the red border around the seal has been on the Guam flag from its initial adoption. The National Geographic flag issue of September, 1934 at page 367 shows the Guam flag in its current form. The only apparent difference is the heartland which appears in green to conform with the seal, where most artistic renditions of the flag show the headland in white (apparently this was first published by Whitney Smith in his Flags of the States and Territories (1970)).

The headland is supposed to be gray. Early illustrations used a dark gray that appears green. Currently a light gray is used making it appear white.
Ralph Kelly, 22 April 1998

The Guam Flag was designed by Mrs. Helen L. Paul, the wife of an American naval officer, and was officially adapted as the territorial flag by Governor Roy C. Smith in 1917. The background of the flag is a striking deep blue, which represents the ocean, accented by a red border. In the center of the flag is an oval figure in the shape of a slingstone used by the ancient Chamoru. The flying proa, a swift, seagoing canoe, typifies the courage of the first inhabitiants who travelled intrepidly across the Pacific Ocean. The coconut tree growing in barren sand depicts the determination of the earliest settlers to overcome whatever natural causes confronted them.

At: http://members.aol.com/_ht_a/magastodu/guahan/overview.htm the image differs slightly from the one above and looks more like the ones depicted in Smith (1975) and in Pedersen (1971).
Jarig Bakker, 12 May 1999

The Guam flag referenced in the September 1934 National Geographic is not the current one. The flag does not have the red border. Mr. Crampton's work references the red border of the flag, not the red border of the seal. Maybe the flag was changed to the current pattern in 1960 as Mr. Crampton mentioned.
Nozomi Kariyasu, 27 April 1998

It appears the flag was officially adopted on Feb 9th 1948 and modified in 1960 when red border was added.

The image sources: Kannik (1958), Handbook of Flags; 1934 National Geographic Magazine
Nozomi Kariyasu, 4 May 2001

Guam

Guam of Territory

Flag of Guam

Flag without the red border