I'm going to agree with the OP, which may mean that the trend down is currently confined to either our heads or to the west coast. However, we've been experiencing measurable, at least by the US Census American Community Survey, downward trends in cycling locally for the past five years.

Just looking around, the college and high school kids aren't hitting the road on fixies (or any other bikes) any more. We've had car share companies come in and apparently successfully target our young folks to the point that I see more of them in those tiny Cars 2 Go than on bikes. When my twenty-something son has friends over, they invariably arrive by car lately; in years past they all came by foot or bike.

It's not weather related. Sure, we have sharply reduced ridership when it rains, but this has been the mildest, driest winter in many years and the trend is obvious in the dry season as well.

I like seeing people ride. I'm concerned that fewer people seem to be doing so for more reasons than the pleasure I get from seeing them, however. The young folks in the current crop have almost all been deprived of independent transportation from day one as mommy and daddy drove them everywhere. If they can't find a way out of it when they reach high school or college, that disturbs me. Sure, it may just be that their vision of the future is markedly different than mine or that of their immediate predecessors, but when I see their projects for their city planning classes they all seem to have accepted that the era of the car is coming to an end.

Hopefully this is just a slight downward blip that feels worse because it comes after a large rise that was driven by the Great Recession.