When I attended a Catholic high school, the school uniform skirts had to be at least one inch below the knee, so that when we knelt on the floor, it was even with the floor.

However, immediately upon dismissal at 3 PM, as soon as the girls were one block away from the school grounds, the girls would hike their skirts up four inches by rolling the waist band. I did not do this as we still could be reported. Among those girls who hiked their skirts every afternoon were those who got expelled later on because they became pregnant. No, they were not raped. This was back in 1960.

In my area, a very well-known "Catholic" preparatory high school has switched to unisex uniforms for all.  Tan chino slacks or shorts, a navy blue golf shirt, and a Navy blue pull-over or button up sweater.  For P.E. and sports they wear navy mesh shorts or pants with a tan T-shirt and pull-over sweatshirt.  They seem to wear the footwear of personal choice, mostly sneakers.  The reason for the genderless uniform in 2014, was the acceptance into the school of LGBTQ students and teachers.  Also, the girls' uniforms in particular slid precipitously from fairly decent in the early 90s, to the present state of degradation. Skirts got shorter and shorter and the blouses became ridiculously tight by about 2000.  For a few years, the girls wore something called skorts, short-shorts with tight skimpy flaps in back and front.  The hems of the flaps reached to about an inch above the short legs!  With this, they'd wear stretch blouses so tight one could sometimes see nipples portruding.  It was truly disgusting, especially on heavy girls!  Then they had a pants option for girls until the present gender neutral uniform.  I know about this because I've driven past the school at dismissal time twice a week for 27 years!  St. Francis of Asissi is surely grieved.  I wouldn't be surprised if one day his statue is seen high-tailing it off the campus.