tl;dr Castro is a lot more male than the Mission.
My old shuttle stop was removed from the approved list by SFMTA. Luckily, my replacement shuttle stop is an order of magnitude closer than the old one; I can now more or less stumble out of bed and be at my stop.
But, one of the things I immediately noticed was the gender differences. At my old stop, I would guess it was about a 60% / 40% mix of men vs. women; I'd guess that is probably close to Facebook as a whole. At the new stop, it seemed like it was closer to 80% / 20% (with a sample size of n = 1).
This made me wonder if there was a meaningful difference in the underlying population that would be driving this difference. Using the US 2010 Census, it looks like the "drainage basin" for the 18th & Castro shuttle stop is 63.6% male, while the basin for the 18th & Church stop is 57.5% male (z = 11.89, p < .001). So, the gender difference can be totally explained by differences in the catchment basin.