What is the symbolism for the use of the white gown for girls for the
traditional high school graduation?

Hi queensandy, 

I take it, this is the view you are picturing – guys in color, girls
in white –

BHS Graduation
http://www.cs.dartmouth.edu/~dwagn/photos/BHSGraduation.jpg

High School Graduation
http://www.harborlightnews.com/this_w47.gif

The short answer to your question is, NONE. There is no symbolism, nor
even a tradition of women wearing white gowns to graduate from high
school.

Here's the long answer ---

As it turns out, girls in white is not any long-standing "tradition"
but is more likely a recent innovation having more to do with style
preferences of the day.

More the norm nowadays is this: Guys in one color, girls in another. 

NVBS – High school graduation
http://nvbs.pvt.k12.ca.us/graduation/graduation21.jpg


Or this – everyone in the same color – which is the historical norm. 
http://www.greece.k12.ny.us/pubinfo/Current%20Events%20Photos/Athena%20Graduation/images/P0001884.jpg


Understand that the whole idea of high school graduation gowns is
based on the traditional academic regalia worn by university
graduates. This American Council of Education website offers an
interesting background on the meaning behind each of the cap and gown
colors and designs traditionally worn by University graduates.

"The assignment of colors to signify certain faculties was to be a
much later development, and one which was to be standardized only in
the United States in the late 19th century."

An Academic Costume Code and An Academic Ceremony Guide
http://www.acenet.edu/faq/costume_code.html


As you can see by that article, colors for university graduation have
nothing to do with the sex of the graduate. They are determined by the
college from which you graduate and by your level of education.

However, in high school there are no different colleges. One color
alone signifies graduation. Early on, graduates from high school
didn't even wear gowns. This picture from 1923 shows the graduation
class just wearing dress clothes. Yes, the women are in white, but
only because white was considered "dressy" in those days.

1923 – no gowns, just white dresses
http://www.eg.bucknell.edu/~hyde/potter/classOf1923.25.jpg

And in some cases, just your "best dress" did the job. 

1920
http://penncrest.iu5.org/WebPages/MHS/Students/GrassRoots/images/THS%201920.jpg


When high schools began to have official commencements and gowns, the
color was the same for both sexes -- black.  If you look at
photographs depicting high school graduates over the course of the
last 60 years or so, you'll notice that both sexes wore black right up
until the late 60's or early 70's (hard to tell with black and white
photographs)

Then, somewhere along the way black was dropped in favor of "school
colors." Suddenly graduates began wearing green or burgundy or even
all white. The separating of male and female into two different color
groups seems to have only appeared in the last 25 years or so, and
even then, only sporadically.  Many high schools still graduate
everyone in the same color gowns.

Here's a little walk through history (note that these are all high
school graduation pictures, not university) –

1932
http://www.madison.k12.wi.us/west/class98/1932.jpg

1936
http://www.madison.k12.wi.us/west/class98/1936.jpg


1942
http://www.isd77.k12.mn.us/schools/dakota/worldwarII/EvieCaseyOld.GIF

1945
http://www.ozzie.net/maryann/4bcd7820.jpg

1951
http://www.nisd.net/images/community/history/nhs-grad-large.jpg
http://www.nisd.net/community/history/

1963
http://www.100megsfree2.com/jjscherr/scherr/images/JacHSGrad.jpg

1965
http://www.whoa.org/65/prunier/sangleylr.jpg

1967
http://www.swhs1967class.com/assets/images/graduation.jpg
http://www.swhs1967class.com/html/group_1967.html

1970
http://www.oakhills.edu/oakhillsarchives/images/1970gr1.jpg

1972  
http://morrisny72.esmartweb.com/Graduation5.jpg

1974
http://www.whoa.org/74/aguon/1grad74lr.jpg

1976
http://www.iss.k12.nc.us/schools/nihs/images/Graduation1976.jpg


1977
http://www.beverlysdomain.com/BevsFamilyPhotos/Graduation1977May-474.jpg

1978
http://www.amador78.org/PhotoGallery/ChrisKearns/Chris%20Kearns%20and%20Kevin%20Kragen-Graduation.jpg


1989
http://www.caam.rice.edu/caam/images/Linda/1989_graduation3.jpg

1991
http://www.davidhibler.com/class91/images/1991.jpg

1991
http://www.geocities.com/okielady_73/bhs91/images/graduation.jpg

1997
http://www.psych.purdue.edu/~mcmurphy/highschoolgrad.jpg

2002
http://www.hemphill.esc7.net/Graduation/graduation.htm


See here for the entire gown history of one school. Notice how they
were all black (or dark – b&w photos) then in 1952 switched to all
white, then back again in 1954. After that they seem to be in color
(blue).
http://www.madison.k12.wi.us/west/gradpic.htm

Here's another set from one school. This one did use black and white
gowns for male and female.
http://goodlight.net/pascalphoto/gradmenu.htm



So, to reiterate the answer to your question --  There is no symbolism
behind girls wearing white to graduate from high school. It's just a
recent innovation and a trend that's likely based on fashion of the
day.

Thanks for your question –

-K~

Search terms –

"Academic regalia" colors

Searched google images for:  

Graduation 1920
Graduation 1925 ..etc

Seems to have good back up on the answer.  Thanks.