I always heard Asian women had the tightest and smallest vagina's and I became interested in them as result. But based on studies from gynecologist and the American Journal of Obstetrics and Gynecology, black women do.
Below is a explanation from a certified gynecologist:
I think torso length and hip width are pretty good determiners for vagina size. It is not the height of of the women (head to foot) which determines the depth of the vagina.
There is definitely a racial difference and also genetic factors which determine the length of vagina. White women give birth to babies with larger heads "on average" so their hips are "on average" broader, and their vaginal opening is also larger. Black women, actually have smaller vagina's. They give birth to babies with smaller heads and have smaller hips. Black women store more body fat on their buttocks, but their hips are actually smaller (men and women). White people also have longer torso's and white women also have longer vagina's. Asian women have shorter vagina's than both black and white women, have wider openings than black women, but not as large as white women. Unlike penis size, the body size/shape of a woman has an influence on vaginal size. Taller women (longer torso) with wider hips will most likely have longer and deeper set vagina. Torso size/length is more significant than actual height. As for men however, a 6' 8" man may have a smaller penis than a 5' 8" man, just like has ears may also be smaller. External organs are not influenced by body size or height, whereas internal organs are.
Thank you

Links to studies that show:
http://www.ncbi.nlm.nih.gov/pubmed/24464469
http://www.ncbi.nlm.nih.gov/pubmed/20042169
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2593128/
http://www.ncbi.nlm.nih.gov/pubmed/10895030
http://www.justanswer.com/ob-gyn/6d52a-women-longer-torso-s-deeper-vagina-s.html
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1283097/
All these links and studies show that black women have smaller vaginal canal's, their pelvic floor muscle strength is stronger than other races and that they have more vaginal muscle thickness. The explanation being black women have more musculature in their PC muscles as well as their vaginal canal's being smaller due to that race naturally giving birth to smaller babies than white or Asian women. Also the rates of incontinence is smallest in black women.
Can anyone give any insight on this? Some of these studies have up to 70,000 women tested and some as little as 33, but each of them have the same findings. They all claim black women have the tightest vagina's.
Also if this is true, will this affect the way we see porn and have any effect on the industry?
Common myth is that vaginal size correlates by race of male with black men being the biggest, white medium and asian smallest.
So most assumed that black women were the loosest (the most undesirable) and asian women as the tightest (most desirable), with white women in the middle. However, studies are showing that the race of male has no effect on vaginal size, its about the size of the babies women of said race naturally give birth to and hips width and apparently from studies black women have the narrowest hips.