When was the 1st lesbian porn film released in the U.S.?
I already Googled it.
I'm not sure of your answer, but it's funny you should bring this question up! Just last Thursday I was reading about "Candy Barr". She is considered the first porn star, after starring the film "Smart Alec" in 1951 at the age of 16. I was on a crazy Wikipedia frenzy going from page to page, I got there after reading she was dating Jack Ruby at the time of the famous assassination (the guy who shot Oswald, who had shot Kennedy).
Her story is actually pretty interesting, she led a pretty wild life, and she writes some decent poetry!
https://en.wikipedia.org/wiki/Candy_Barr
Sorry for the segue, I just found this post coincidentally similar to what I was reading about recently. Anyways, onto your question, I don't know the answer, but I did do some wiki'ing to help find out!
List of vintage porn:
https://en.wikipedia.org/wiki/Category:Pornographic_films_by_decade
I originally thought based on the description in Wikipedia that it was: El Satario in 1907, assuming you mean pornography that includes .
https://en.wikipedia.org/wiki/El_Satario
"A group of young women is frolicking in the countryside. This leads to them having sex with each other. Then the devil appears and forces one woman to receive and perform oral sex and then have sex with him. Then the other women come and put him to flight."
Sadly investigating further, the women do not have sex with each other.
You could argue this might be it? "Le ménage moderne du Madame Butterfly." from 1920.
https://en.wikipedia.org/wiki/Le_ménage_moderne_du_Madame_Butterfly
"Le Ménage moderne du Madame Butterfly[1] is a bisexual, hardcore pornographic film from France. It is notable for being the earliest known adult film to incorporate bisexual and homosexual intercourse"
Initially there is a lesbian scene (first 4 minutes) but it's quickly interrupted by a man.
http://fr.xhamster.com/movies/324649/vintage_french_porn.html
"Mona The Virgin Nymph" (1970) looks like the earliest I can find that didn't end up with a man interrupting. See 22:00.
http://fr.xhamster.com/movies/738364/mona_the_virgin_nymph_1970.html