"September is Just the Beginning" banners that mysteriously appeared on Prospect Heights streets mysteriously removed

Last night, some 24 hours after a few dozen "September is Just the Beginning" banners appeared on light poles on Prospect Height streets near the Barclays Center arena, most were removed.

Why? I'm hoping to find out.

Thursday evening on Carlton Ave.

Thursday morning on Carlton Ave. (not same spot)

Photo by Tracy Collins

Friday morning on Sixth Ave. 

Thursday morning on Sixth Ave. (same spot)

Here's what may be the only one remaining, as of this am, on Carlton Avenue below Bergen St.