PARK CITY, Utah — Somewhere in the 600 or so miles between this mountain town, host to the Sundance Film Festival, and the movie factories of Hollywood, female filmmakers seem to vanish.

Of the top 100 movies at the 2010 box office, three were made by women: “The Last Song” (No. 51), “Nanny McPhee Returns” (96) and “Ramona and Beezus”(100.) Meanwhile, 27 of the 117 features playing at this year’s festival have female directors.

The Oscar-nominated actress Vera Farmiga is here with her high-profile directing debut, a haunting portrait of self-discovery called “Higher Ground.” The newcomer Cindy Meehl has one of the festival’s most talked-about documentaries in “Buck,” about bonds between people and horses. Maryam Keshavarz’s ambitious first feature, “Circumstance,” focuses on teenage lesbians in Iran.

What’s behind this cinematic Bermuda Triangle?

If the evidence is cut and dried, an explanation is not, say people like Cathy Schulman, the Oscar-winning producer who is president of Women in Film, a nonprofit organization dedicated to advancing sexual equality in moviemaking.