Tuesday morning I took the SS-9 from Greyhound (since I went to my parents in Atlanta for the weekend) to Florida Coastal. Much to my surprise, the bus was totally full. I'd been on full buses once or twice since moving to Jax but never seen the SS-9 full.
What was the deal? Here's my explanation: normally I take the SS-9 northbound (Mandarin towards downtown) in the morning; since the SS-9 begins in relatively affluent South Mandarin, not too many people take the SS-9 from suburbia to downtown in the morning (especially after rush hour; I usually board at 9:20 or 10:20, long after most 9 to 5 commuters are at work). When I take it southbound from downtown (maybe 6 to 7ish), it is more crowded - but still, the main ridership is comprised of car-owning suburbanites.
By contrast, reverse commuters* from the North and West sides (who are more likely to be carless and/or low income) are more likely to go southbound away from downtown in the morning and northbound at night. Since low income bus ridership is higher, it would make sense that morning bus ridership is higher for reverse commuters than for downtown workers, and thus higher as you go south from downtown to Mandarin.
So what? Is there any point to this story?
Yes. For as long as I've lived in Jax, I've heard people whining "Why should we have more buses if the ones we have are empty?" But my story suggests that even a bus that is empty at some point is full for part of its route. My SS-9 began (full) downtown, then got less and less populated as it dropped off customers in Baymeadows and Mandarin.
Then it terminated (probably empty) in South Mandarin and started going north- but it wasn't necessarily full going towards downtown, because it dropped off customers as well as picking them up.
Once it got downtown, its only remaining riders were those who had business downtown. So as it was heading north into downtown it might not have been that crowded.
But once it went to the main downtown bus terminal, it picked up a bunch of southbound riders, became relatively full with reverse commuters, and the cycle began again. So I suspect if you were downtown and you saw the bus entering downtown it looked pretty empty except during rush hour. But leaving downtown (especially during rush hour) it was probably not so empty.
*By "reverse commuters" I mean people heading away from downtown towards suburban jobs.